The Light Source Purlin Clamp 1/2" is perfect for installing almost anything to bar joists, purlins and I-beams up to 1" thick. A 1/2"-13 x 2.5" fully threaded square head set screw is provided for locking onto the structural member. A 1/2"-13 x 1" grade 5 Hex Head Bolt is supplied to connect the load. Or use a 1/2"-13 tpi threaded rod to support a load at any length. The Purlin Clamp has Micro-grooves for a secure connection to beam. The 1/2" fastener Purlin Clamp body is extruded from aircraft grade aluminum and is 1" thick.