Arisaka Defense Hand Stop, Black, Picatinny, Anodized IDX-M The Patented Arisaka Indexer is a continuation of their low profile" minimal control accessories. It was developed due to end-user demand for an M-Lok version of their Finger Stop for Picatinny rails" and features a slim front-to-back profile and slight radius across both faces. The Indexer can be used in a variety of ways" but the main intent is to place it between two fingers (usually index and middle). This typically places it further forward on the handguard" which also means it doesn't get in the way when transitioning to kneeling or prone shooting positions" where most people move their support hand towards the rear. Used in this manner" the Indexer makes it much easier to pull the rifle into your shoulder and maintain control while shooting. Additionally" the wider" flatter profile of the Indexer functions very well as a hand stop or barricade stop" and also works as a forward limit to prevent your fingers from slipping off shorter handguards onto a hot barrel or suppressor.