Blue Force Gear Snap Hook (HK Hook) - 1in

Snap Hooks, also known as HK Hooks, are quick attach hooks for mounting your sling to eyelet mounts, like seen on HK firearms and FN's SCAR platform, etc.  

The BFG Snap hook also has an eyelet hole that allows you to attach another snap hook to itself, allowing for convertible 1-Pt configuration with no additional hardware needed.  The 1" slot accomodates slings up to that width.