This Henry Big Boy Scope Mount is for Big Boy Rifle that are drilled and tapped on the top of the receiver. This is an extremely versatile Picatinny Rail Henry Scope Mount that can accept either Picatinny or Weaver style rings in a wide range of positions. Installation is easy and instructions are included.Specifications and Features:Henry Repeating Arms BB-RSMPBig Boy Scope MountPicatinny RailFor: Drilled and Tapped Big Boy ReceiversAccepts Weaver or Picatinny Style RingsBlack