The Saris H3 Plus takes the flatter drive-side shell of the seemingly-discontinued H4, sticks it on their H3 along with the word “Plus” and now it’s 12-speed compatible. It still comes with a standard HG freehub body, but the new shape adds clearance for 12-speed derailleur cages to move far enough inboard to reach the largest cog, where as the original H3’s slight curve does not.
It’s still very quiet (just 59db @ 20mph), has +/- 2% accuracy & 2000w max resistance, simulates 20% climbing grades, and fits up to 42-tooth 8/9/10/11/12-speed MTB cassettes. Headless Mode lets it ramp up just like a fluid trainer when not paired with any apps. MSRP $799.99; XD/XDR freehubs sold separately. (Here’s a cheap 12sp cassette if you need one)