This 4" Rail Adapter with sling swivel receptacle replaces the Two sling swivel studs on the for-end of your rifle to enable the quick detach of the Evolution Bi-Pod. There is a long slot to accomodate the variety of two sling swivel stud type stocks that are on the market. This Rail Adapter includes an anti rotation flush cup receptacle. Includes Screws and hardware for installation. $39.99
 
Minimum distance between attachment point bolt holes 1.5" 
Maximum distance between attachment point bolt holes 3.5"