Chrome plated zinc. Top mounted.Includes: (2) Rowlock horns: OD shank: 1/2", Shank length: 1-3/4"Between horns: 1-3/4" Complete with locking pin(2) Rowlock socketsPlastic bearingsDimensions: 2-7/8" x 1-1/8" x 1-1/8", ID Hole: 1/2"