This is a butt hook for a Sanseigne biathlon rifle stock. It has a completely different mounting system than the originals. It mounts exactly the same way as a hand stop. This system is far stronger, as it will be held with stainless steel instead of thin plastic. Also do to the lack of a set screw, the butt plate will not be damaged from tightening it. It is the same length and follows a similar profile as the original Sanseigne top butt hook.
This REQUIRES "MOUNTING BLOCK", AND A M6-1.00x12mm SCREW! Screw is availiable at most hardware stores.