Valley 75637 1/2" and 5/8" Stainless Steel Receiver Lock, Sleeved Barbell Stainless steel receiver lock with 2 keys. Manufactured and stamped "Master Lock," and carded as Valley. Fits both 1/2 inch (13mm) (sleeve off) and 5/8 inch (16mm) (sleeve on) receiver tubes. "Weather Seal Tough." Barbell series.