Simpson Strong-Tie® Quick-Lock Pier Boot® spacers are designed to support a reinforcing steel cage within a drilled shaft with a concrete cover requirement. All of our Quick-Lock Pier Boot spacers are made of durable, noncorrosive plastic. Installation is accomplished in seconds by simply pushing the Quick-Lock Pier Boot onto the end of a vertical bar. The 3-in. Pier Boot fits rebar sizes #5 through #18, and the 6-in. Pier Boot fits rebar sizes #6 through #18.