Master Lock 3.5" Long Shackle Barbell Lock is chrome plated and is designed to improve wear as well as provides corrosion resistance. It is made from solid brass offering long lasting life. This lock fits standard coupler latches and features a water tight cap which protects the lock. It consists of 4-pin tumbler mechanism which resists picking. Master Lock manufactures this item to 1/4 inch diameter plus or minus .05”.