Rounded Metal Slave Collar. The Rounded Metal Sub Collar will look amazing around the neck of your obedient pet. Made from stainless steel for the added sensation of cold metal against the skin, this hefty collar comes in one size (37cm) and is lockable with a Hexagon socket screw (Allen key included). A durable O-ring provides an anchoring point for any leash, rope, or chain. Enjoy a different type of collar experience with the Rounded Metal Sub Collar.