Bought this a month ago from Armaspec. It's the Carbine (3.3oz) weighted version - recommended by Armaspec to replace the H Buffer and flat spring in my .300 Blackout SBR.
Took it to the range twice. It worked for all ammo weights, super to sub except for one, my preferred (of course) 200 gr Winchester Super Suppressed.
The attached video is very good. It shows how to disassemble and reassemble if you want to use different weights, which are available from Armaspec.