This Jacobs Drill Chuck Key, Type K3 (3651D) features nickel thumb grip styles to increase leverage and user comfort. Soft steel handles limit the potential for dangerous fracturing under excessive load. Self-ejecting models with spring-loaded ejectors ensure key disengagement after tightening. Never apply extensions, pliers, wrenches or 'cheaters' of any kind to chuck key handles. Do not subject chuck key handles to hammer or other impact blows.