Pro-lock is used to anchor the Snareweight to non-metal hoops like die-cast. Made of solid brass. Pro-lock incorporates an arched magnet to attract to the magnet of the Snareweight through the die-cast hoop. It has a slot that the Snareweight drops into, then creates a floating lock to secure damper. The Snareweight with a Pro Lock is as good as it gets for dampening and road worthy durability.