Ade Advanced Optics Mosin Nagant Dovetail and Weaver Picatinny Rail Mount Adapter Length: 3.9" ,Weight: 2.3 oz 3/8"Dovetail To 7/8"Weaver Mount Base attaches to dovetail converted to weaver Material: High Quality Aluminum Rail Type: Picatinny/Weaver, 5 Slots