Kocao Sexy Slave Lockable Neck Collar Restraint Locking Bondage Fetish Costume Silver Condition:100% Brand New Set Include: 1pc collar Material: Stainless steel The collar is about 4mm thick and 20mm wide, 120mm internal diameter and about 15 inch in circumference. It is lockable and openable with a steel thread. The back of the collar is cut a "M" shape, Friendly Tips: The size is measured by hands, please allow minor error of measurement .