USED This 1 groove sheave measures; 2 1/2" for the outer diameter, 1 1/4" for the inner diameter which is measured according to standard pulley measurements. The sheave measures 3/4" thick excluding the hub. The hub itself measures 1/2" for the inner diameter where the shaft would be located. The groove on the inside of the shaft hole is 3/16" by 1/8". The original manufacturer is not known; however, there is a CDG with a part number of 116 250-B printed on the sheave.