Supertech BMW 6mm single groove valve keeper

Supertech BMW 6mm single groove valve keeper, part number KPR-6S/7. Fits BMW single groove valves and many more. Application list:
http://www.supertechperformance.com/p6810-kpr-6s-7-6mm-single-valve-lock-conversion

Sold per/pcs, 2pcs needed for each valve.