I would believe that only Planet X sell Selcoff, and that it's either a replacement freehub or a new wheel
Planet X list spare freehub bodies under Components > Wheels > Spares (£40).
There are 6 options listed, all for "Selcof 35/45/55 Carbon Wheelset", with two apparently identical options each for Shimano 11/12, SRAM XDR and Campag. The two Shimano options have different codes (WSSECDWFBSH1112 and WSSECWFBSH1112), the SRAM and Campag pairs also have DW and W codes. The codes don't show on the shopping basket lines.
The Shimano and SRAM options say "Older 4 pawl model, this cannot be used with the newer 6 pawl version of the Wheels"; the Campag options don't. It looks from your photo above like you've got the newer 6-pawl version.
One might guess that the 6 options may be 4 and 6 pawl freehubs for the 3 spline patterns, and they've mucked up the listing text by copy/paste.
Unfortunately, finding out and ordering will mean ringing up and hoping you get someone competent and helpful, or protracted email ping pong.