The City Theatrical 135 Tee Head is the male part of the Moving Light Hanger System. The Tee Head works in conjunction with the Tee Slot to hang a moving light in the same place each time. The 135 Tee Head comes with a 1/2"-13 bolt, washer, a cupped tightening knob, and a rubber clip. The Tee Head settles into a groove in the Tee Slot to temporarily hold the head in place even when the Tee Head knob isn't tightened. Place the rubber clip on spare threads below the knurled tightening knob during transportation to prevent the tightening knob from loosening.