Truths Entrygad Dual arm operator number on the arm reads 20755 center mounting hole center of mounting plate to the end of straight arm measures 10 1/2″ small arm end with clip measures 3 3/4″ from center hole in mounting plate to end of arm off set is up. common replacements numbers are 31538, 31539,30841, 30842, 30472, 30470, and 20755. Please verify your dimensions before ordering.