MacDaddy Overmold Stopper fits a 3/8" rod, deep 1/4" groove. Great for crossbows or you can use them on compound bows also. This over-molded stopper has a soft polymer molded over a durable polymer underneath. Fit's all 3/8" rod string suppression systems. One of the great benefits of this stopper is the deep A 1/4" groove to catch the string.