Gemtor sba-141, sliding beam anchor – auto lock features: stainless steel and high-strength aluminum construction installs in seconds without tools mounts to top or bottom horizontal beam flange unique design prevents snaphook gate from contacting edge of beam follows a worker’s movement along an i-beam stainless steel rollers allow anchor to glide along top of beam and last longer than nylon pads lightweight yet extremely strong and durable automatic rotary locking system for fast secure attachment to beam, fits beams from 4″-14″ wide and up to 1 1/8″ thick.