The details
This answer covers the Flair 58 lever machine in all its revisions (58, 58x, 58+), which share the same 58mm portafilter platform.
- The Flair 58 ships with a stock 58mm basket, and Flair sells both standard-flow and low-flow versions as accessories.
- Because the portafilter is a standard commercial 58mm format, third-party precision baskets are the most common upgrade: owners widely run VST (ridged or ridgeless), IMS, Pullman and Wafo baskets without modification.
- Ridgeless baskets are generally preferred in the Flair 58 portafilter because they seat and release cleanly, but ridged baskets fit too.
- Nominal capacity matters more than brand: common double baskets in the 18g to 22g range are the mainstream choice. Very deep high-capacity baskets reduce headspace under the plunger, so check the basket's stated depth against your dose before buying.
Why the 58mm standard matters here
Flair built the 58 around the commercial basket size on purpose. Everything downstream of the basket follows the same standard: 58mm puck screens, 58mm distribution tools, and tampers sized for commercial baskets all work. That means accessories you buy for the Flair 58 carry over if you ever move to a 58mm pump machine, and vice versa.
The one Flair-specific consideration is the plunger and valve assembly above the basket. It is designed around normal basket depths, so exotic triple-depth baskets are the only category where owners report checking fit first. For ordinary single and double baskets there is nothing proprietary to worry about.
What owners actually do
The most repeated pattern in the owner community: keep the stock basket for learning, then move to one precision basket and stay there. High-extraction baskets from IMS and Wafo are popular with light-roast drinkers because they pair well with the Flair 58's manual pressure control, while VST is the usual pick for people who want consistency above all. Owners also note that an 18g basket from one maker can behave differently from an 18g basket from another, since hole count and hole geometry differ, so expect to re-dial your grind after any basket swap.
The trap to avoid
Do not buy a basket by capacity alone. Two traps come up repeatedly. First, pressurized or dual-wall baskets have no place here: the Flair 58 is designed for unpressurized baskets and a proper grinder. Second, some sellers list "58mm" baskets that are actually sized for specific superautomatic or pod systems with different rim shapes. Stick to baskets marketed for commercial 58mm portafilters. If a listing does not name the rim standard or show it fitting a standard portafilter spring, skip it.