That model name is an IMS product code — series, cup count, height and hole pattern are all encoded in it. IMS basket codes, decoded explains how to read one, and lists every code covered here.
The 28.5mm height in IMS’s B70 convex competition line — the deepest convex basket IMS makes, rated up to 27 g of a light roast.
A convex basket has a raised centre to the floor, so the puck is fractionally
thinner in the middle than at the edges. The intent is to counter the tendency
of water to find the centre first: the shorter path through the middle is also
the denser one, which evens out flow across the bed.
Geometry is otherwise standard B70 — Ø70mm border, Ø60mm body, ridgeless, 715
holes of 0.30mm over a Ø49mm perforated area, for a Ø58/58.4mm tamper.
IMS publishes the whole convex family’s capacities on one table, and the heights
are a dose ladder rather than quality steps:
Pick by the dose you actually pull. Note how much the roast level moves the
figure — the same basket takes several grams more of a light roast than a dark
one, because lighter beans are denser.
Ridgeless, so it suits a bottomless portafilter well. Same official B70
compatibility as the rest of the series; Gaggia machines take the narrower B68
series and are deliberately not cross-referenced.
Other items confirmed to fit machines this one fits — useful if you're kitting out a single setup. The count is how many of those machines overlap; nothing here is a new fitment claim.
What size portafilter is the IMS B70 Competition Convex 2 Cup H28.5 (B702TCH28.5E) for?
It is a 58mm basket, 28.5mm deep, for 58mm portafilters.
Is the IMS B70 Competition Convex 2 Cup H28.5 (B702TCH28.5E) pressurized?
No — it is a non-pressurized (single-wall) basket, for freshly ground coffee.
Does the IMS B70 Competition Convex 2 Cup H28.5 (B702TCH28.5E) fit 54mm machines like the Breville Barista Express?
No. It is a 58mm basket, so it does not fit Breville's 54mm machines or any 54mm portafilter.
Which machines does the IMS B70 Competition Convex 2 Cup H28.5 (B702TCH28.5E) fit?
Breville Oracle; ECM Estetika; ECM Mechanika MAX II; Flair 58; La Marzocco GS3; La Marzocco Linea Micra; La Marzocco Linea Mini; Lelit Bianca (PL162T); Lelit Elizabeth (PL92T); Lelit Kate (PL82T); Lelit MaraX (PL62X); Lelit Victoria (PL91T); Rancilio Silvia; Rancilio Silvia Pro; Rancilio Silvia Pro X; Rocket Espresso Appartamento; Rocket Espresso Epica; Rocket Espresso Giotto Fast; Rocket Espresso Mozzafiato Fast; Rocket Espresso Porta Via; Rocket Espresso R Nine One — each confirmed against manufacturer sources (listed below).
Sources
https://www.imsfiltri.com/filters/B702TCH28.5E.html(archived) — Official IMS Filtri product page ('B702TCH28.5E'), read firsthand 2026-08-11. Specs verbatim: 'Border: Ø 70 mm', 'Body: Ø 60 mm', 'Height: 28.5 mm', tamper 'Ø 58/58.4 mm', 'Ridge: Ridgeless', '715 Holes' of 'Hole Diameter: 0.30 mm' in a hexagonal pattern over a 'Perforated Area: Ø 49 mm' optimized for the convex shape. The page's capacity table gives this height as 19/22 gr (dark roasted), 22/25 gr (medium) and 23/27 gr (light), within a family running B702TCH20E (20 mm) through B702TCH28.5E (28.5 mm).
https://www.imsfiltri.com/IMS-competition-Catalogue.pdf(archived) — Official IMS Competition Series catalogue, read firsthand 2026-07-04, whose 'For tamper 58 / 58.4' B70 compatibility list names La Marzocco, Rancilio, Lelit, Rocket, ECM and 'BREVILLE (The Oracle)' among the fitting brands — and 'FLAIR ESPRESSO (58)', which is why the Flair 58 is cross-referenced here; Gaggia is assigned to the narrower B68 series, so B70 baskets do not cross-reference Gaggia machines.