58mm to 49mm Step-Down Portafilter Basket

Unlock new dimensions of flavour with the INTROVERT 58mm to 49mm step-down espresso basket, designed for clarity, balance, and shot stability.

What is a step-down espresso basket?

A step-down espresso basket fits a standard 58mm portafilter but has a smaller extraction chamber, 49mm for this instance. Given the same dosage size, this results in a thicker espresso puck and promotes more balanced shots, more even extraction, more even flow, and ideally more pronounced flavours with less harshness as a result. By having a taller aspect ratio espresso puck, you rely more on the thickness of the coffee puck to provide its own resistance rather than choking it with a finer grind on a thinner puck. With the coarser grind afforded by the thicker puck, you decrease the chances of channelling, dry spots, and uneven extraction that usually results in harshness, astringency, and bitterness. Overall, it brings the forgiving, high-aspect-ratio performance of 49mm baskets to your 58mm machine, and makes low-dose and precision shots easier and more consistent.

 

Beta Edition V0.5 Pre-Order - Limited Release Starting On October 5th, 2025 at 9:00AM PDT

Follow the Beta progress on my blog

Well, the Alpha batch has been produced and shipped and from testing with many people for the last few months, it's safe to say that the basket works aside from some fitting issues 😉. Feedback is still coming in from the rest of the Alpha testers and I'll be using the feedback to design the Beta version.

The Beta version will be focused on refining the details to maximize workflow smoothness and further improving shot quality, as well as greater compatibility for a wider range of shower screens and dispersion blocks. Additionally, we will be exploring additional variables for the basket together, such as flow rate and capacity. These are made for fellow espresso enthusiasts and testers, at an exclusively and significantly reduced price. Last time with the Alpha, I sold out of 100 baskets within 13 hours, and have been asked constantly about the next batch. For the Beta, I firmly believe the design is moving towards an optimal one, and thus I'm releasing a larger batch.

Here's the quantities of the Beta batch I'm launching with:

• 50x 16-18g | Low Flow
• 150x 16-18g | Medium (Standard) Flow
• 75x 16-18g | High Flow 
• 75x 20-22g | Low Flow 
• 75x 20-22g | Medium (Standard) Flow 
• 75x 20-22g | High Flow 

Being a Beta design, there may still be some unexpected minor issues with the basket. Just as the Alpha feedback is shaping the future versions, your feedback will help refine the final production model, giving you a chance to shape the future of espresso gear.

Additionally, having a large sample size with various machines, portafilters, and workflows will help ensure that it is more compatible with more setups!

Please keep in mind that every single aspect and detail of the basket and accessories may be subject to change in future iterations.

The current estimate for shipping the Beta batch is sometime between Feb-May, 2026. The delivery estimate that you may see at checkout and order confirmation will be incorrect.

Key Features

(Some details shown below depict the Alpha version. Beta will have the same core features, but with different dosage and flow options, as well as some optimizations. Additional details will be filled in December following Alpha feedback)

I will aim to make Beta V0.5 a little larger in diameter to fit more shower screens and dispersion blocks.

CNC-machined From a Solid Block of 304 Stainless Steel
Unlike almost all of the baskets out on the market, which are are stamped, this basket is CNC-machined from solid steel. This yields maximum precision, perfectly straight walls, much sharper and precise edges. The thickened base means it has little to no visible flex during the shot, up to 9 bars of pressure. Flexing during the shot will negatively affect consistency because the shape of the puck is actively changing and may focus the flow towards the center and, in the worst-case scenario, induces channeling. The straight walls and sharper edges allow for holes to be placed all the way to the edge, which allows for maximum extraction consistency (more explanation below: "Vertical Walls" and "Optimized Hole Pattern...").

 

Compatible with 58mm Portafilters
The upper portion of the basket before the step-down fits standard 58mm portafilters and machines, just like other 58mm baskets. It may also work with 58mm dosing rings and some 58mm puck/mesh screens, though the INTROVERT custom 58-49mm Step-down Dosing Ring 49mm puck/mesh screens would be more optimal. One area of focus for the Beta version is to make it fit more 58mm machines.

49mm Extraction Zone
Focuses flow through a 49mm diameter extraction zone, enhancing clarity and balance. Pairs well with manual 49mm tampers. If you use 3rd party leveled tampers, they need to have extra long reach. My custom leveled tampers from the Premium Accessories Bundle will fit either directly on the basket or on the custom step-down dosing ring

Vertical Walls
The perfectly vertical basket walls mean that there is no diameter change throughout the entire extraction zone, and therefore not forcing any pressure changes the deeper down the basket it goes. Note that your tamper or puck/mesh screens will fit the same at any depth. One difference in workflow you will find vs other stamped or tapered baskets is that the spent puck will be more stubborn to get out. It will need more or harder knocks to get the puck out, or you can use my Silicone Bellows to effortlessly pop it out from the bottom.

Angled Step Down
While a dosing ring would help with dosing into the 49mm zone, the basket can still be dosed without it. The angled step down ensures that all coffee grounds will easily and satisfyingly fall down to the 49mm zone without getting stuck at the ledge when you tap it or wiggle it around.

Ideal for 16-18g (Medium Dose) or 20-22g (High Dose) Espresso

The Beta edition comes in two different sizes, the 16-18g version and the 20-22g version. Actual capacity will vary with the beans, roast level, and grind size used. 

Version	Dosage
(Future Planned Version)	Low (TBD ~10-14g)
Alpha V0.1 & Beta V0.5	Medium (~16-18g)
Beta V0.5	High (TBD ~20-22g)

 

16-18g (Medium Dose)

This size is optimized to fit 16-18g of coffee with less headspace and resulting standing water after the shot. The custom step-down dosing ring is required to prep a dose of 16-18g, and you tamp through the dosing ring so that the resulting puck height is very close to the top of the 49mm zone.

20-22g (High Dose)

You can expect the same workflow on this size basket as the 16-18g version if you're dosing for 20-22g. However, this basket is more versatile and allows for lower doses as well, with the tradeoff of a lot of extra headspace. When dosing about 16-18g in this basket, the loose grounds can already mostly fit in the 49mm diameter zone, and you can tamp without going through the dosing ring. Expect a lot of standing water at the end of the shot unless you have a machine with residual pressure after the shot.

Optimized Hole Pattern and Coverage For High Extraction
Precise laser-cut holes that are evenly spaced in a layout inspired by the Fibonacci sequence. The whole array stretches all the way to the absolute edges of the basket to promote maximum evenness and smoothness in flow because there's no change in diameter throughout the entire depth of the puck. The Beta Medium Flow version is designed to have 1001 holes with 3.6% of the surface area comprised of holes, targeting a medium flow rate (this could still end up being too high or too low).

Version	Flow	Holes	Hole Size	Hole Coverage Area %
Beta V0.5	Low	TBD	TBD	~0.5-2%
Beta V0.5 (& Alpha V0.1)	Medium	1001	0.30mm (300 microns)	3.6%
Beta V0.5	High	TBD	TBD	~5-15%

Components Overview:

For Beta Edition V0.5:

	Beta V0.5 Basket + Starter Bundle	Premium Accessories Bundle For 58-49mm Step-down Basket Beta V0.5 (Sold separately)
1x INTROVERT 58mm to 49mm Step-Down Espresso Basket (Beta V0.5 Edition)	✔️
3D-Printed Dosing Ring Custom designed to fit on the top of the basket and covers the step-down transition zone so that the entire hole is 49mm in diameter.	✔️
3D-Printed 49mm Simple Tamper A simple 49mm tamper that can tamp through the dosing ring	✔️
3D-Printed Portafilter Stand A simple stand for your 58mm portafilter to rest on while using this step-down basket, as it lets the basket extend down below the portafilter but not touch the counter top.	✔️
Feedback Form Link In exchange for your feedback, you'll get a coupon for a future iteration of this basket, if it comes to fruition. I'll have a system for feedback set up by the time the basket ships.	✔️
Bespoke Metal 58-49mm Self-Leveling and springed tamper Fits inside the step-down zone as well as on the custom 58-49mm dosing ring Modular plate and tamp pieces will allow tamper to work on future INTROVERT baskets		✔️
Bespoke Metal 58-49mm Dosing Ring Custom designed to fit on the top of the basket and covers the step-down transition zone so that the entire hole is 49mm in diameter.		✔️
49mm Steel Puck Screen A non-mesh style puck screen with thicker steel and lasered holes.		✔️
49mm Steel Spring An experimental piece to test resistance against the expansion of the puck during shot		✔️

(Optional Premium Accessories Bundle can be purchased on a separate listing here.)

Every individual accessory will also be listed individually soon.

Requirements (Not Included):

• 58mm bottomless portafilter
  • The basket is taller than usual baskets, which means it will likely not fit on any portafilters with a closed bottom
• Espresso machine with 58mm grouphead

 

Featured By The Community:

Slowpresso by Home Cafe By Charlie

Unboxing and shot by Pbrewinghouse 

Used on Ikape K2 Pro by fused_visions

Timeline:

Feb-May 2026: Beta V0.5 to be shipped

December 2025: Beta V0.5 Design to be set and manufacturing to begin

October 5, 2025: Beta V0.5 Pre-order begins

September 25, 2025: Alpha V0.1 Started Shipping to all testers and feedback stage has begun.

May 13, 2025: Announcement Day for Alpha V0.1

 

Disclaimers / Notes:

Images are for reference purpose only. They may not entirely represent the final form of the Beta Edition basket. Please join this Beta test at your own risk, as there is always a chance that the basket may not be compatible with your equipment, just like with the Alpha. I won't be able to provide refunds for it once I ship it out. You may cancel your Beta order on or before December 31st, 2025 for a full refund. If the spots fill up, you will have to wait until someone else gives up their spot to join. If you join and decide to cancel your order, you will also have to wait for the next free spot.

If you're an Alpha tester and would like to use your coupon on the Beta version, please reach out to me, and I can retroactively apply it even if you ordered it at full price once your feedback is confirmed (no rush!).

Original disclaimer for the Alpha V0.1 Version:

"With all that said, while I'm super excited to release this product, it is currently in Alpha state, which means it may not work optimally, and at worse, may not work at all. Every single aspect and detail of the basket and accessories may be subject to change in future iterations."

 

A note on US Tariffs:

Duties will be pre-calculated at checkout for orders destined to the US. Since the Beta baskets will take a while to produce, I don't know what the situation will be like at the time of shipping. If there are adjustments needed at the time of shipping, I will reach out to you again.