The details
This answer covers the Profitec Go single-boiler machine in all current color variants, which share the same group.
- The Go's group accepts the E61 portafilter standard: 58mm baskets with the common two-lug mount, the most widely supported format in espresso.
- Profitec's own bottomless portafilter is the factory-match option, sold for its E61 machines and the Go, and Profitec also offers a modular version with swappable spouted and bottomless ends.
- ECM bottomless portafilters fit as well. ECM and Profitec are sister brands and their 58mm portafilters interchange.
- Third-party E61 bottomless portafilters, including popular options from Normcore and various angled-handle makers, list the Profitec Go by name and fit the group.
- Standard 58mm precision baskets (VST, IMS, Pullman, Wafo) drop into any of these portafilters.
What to check before buying
Fit is the easy part. The practical differences between options are ergonomic. Handle angle matters on the Go because clearance between the group and the drip tray is finite: an angled-handle portafilter sits differently under the group than a straight one, and tall cups reduce the remaining space under a bottomless basket. If you routinely brew into a tall glass, check the maker's stated clearance against your cup before choosing an angled design.
Basket inclusion is the other variable. Some bottomless portafilters ship with a high-extraction basket in the 18g to 20g class, others ship bare. If you already own a precision basket, a bare portafilter avoids paying for a duplicate.
What owners actually do
Go owners in the community usually go one of two ways. Buyers who want a guaranteed factory match buy the Profitec or ECM bottomless portafilter and are done. Budget-minded owners buy a third-party E61 bottomless with a wooden handle and included basket, and fit reports for the Go are consistently good since the group is a true standard. A common companion purchase is a precision basket and puck screen, because the entire point of going bottomless is diagnosing spray and channeling, and a better basket makes those diagnostics meaningful. Expect to re-dial your grind slightly after switching from the stock spouted portafilter and basket.
The trap to avoid
The trap is diameter confusion. "58mm" refers to the basket, not to a universal mount, and a small number of machines from other brands use 58mm baskets in non-E61 mounts. That trap does not bite the Go, which is genuinely E61-pattern, but it means you should buy portafilters described as E61-compatible rather than merely "58mm." Also skip listings that only name unrelated proprietary systems. If a listing says E61, or names the Profitec Go, ECM, Rocket or Lelit E61 machines, it will lock into the Go's group.