When mounted on the Pivot Base and hit, this Throom KNOCKDOWN Target reacts and falls over backwards. It stays down until you reset it manually or by pulling on a string. Bullets pass through the KNOCKDOWN Target and the Pivot Base because they are both made of SHOOT-THROO, their tough, flexible, self-healing polymer.To mount a KNOCKDOWN target onto its Pivot Base, you simply snap it into place. Then secure the Pivot Base to your softwood target stand with (4) wood screws or with (2) THROOM Nuts & Bolts.