Sparcraft Stainless steel Sheave Box for 1/2"-9/16" halyards, 7 5/8" long 1 3/8" wide , 4" high overall 6 3/8" mounting holes on center, 1/2" axle pin, The Derlin Sheave is 3 3/8 x 3/4" with 1/2" center . PRICED by the Single Unit. we have several available    May be viewed 38 Buckley Ave. Rising Sun MD. by appointment. Ups, USPS  & FedEx shipping shown   Local Pickup is Rising Sun MD. 21911