Best and Lloyd tank mount oil pump plunger bucket / cup, leather, 15/16 inch (24 mm), 1/4 inch shaft hole, + pump gasket. Suits Veteran and Vintage machines with Best and Lloyd oil pump on tank eg BSA, Premier, AJS and many more. See BT-DJ-BLoilpump-gasket for the pump gasketOriginal Part Number:L12 - leather cup gasket