Top Mount Aluminum Scope Base, Black, 90, Marlin 39A

Each Weaver base is machined to the tightest tolerances for a custom fit. They are designed to fight the effects of recoil with a square-cut notch that precisely mates to the sturdy cross bolt in every Weaver detachable ring. - Fits: Marlin Models 39A(round barrel) & 39A (Octagon barrel)