I'm thinking it might actually be this part which is specifically for the BMW Performance seats. It says it's compatible with the E9X M3, but not for the 1M. But the link to the part you sent me also says it's not compatible with the 1M.
https://www.ecstuning.com/b-genuine-...s/61122155580/
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Current: Z4MCoupe, Interlagos Blue, Carbon Extended Leather, Sat Nav, Heated Seats, Supersprint Exhaust, BBS CH19's, Stubby Aerial. AND E82 1M, Alpine White
Sold: 3 x 130i (White, Red & Black), Mk4 VW Golf R32, '03 Reno Clio Sport