3M DBI-SALA 2103143 Trolley For I-Beam For Use w/Self Retracting Lifeline (Fits Beam Flanges 3"-8" In Width Up To 11/16" Thick), Gold Extremely rugged and corrosion resistant Installs onto 3 in to 8 in wide I-beam flange (76-203cm) up to 11/16" thick (17cm) Complete hands-free horizontal mobility Ideal for use with self retracting lifeline Trolley fits 3 in to 8 in wide I-beams (76-203cm) up to 11/16" thick (17cm) Trolley for use with self retracting lifelines on horizontal beams Attachable anywhere along beam including midpoint Trolley guards protect the wheels from damage and keeps beam clear of debris Fits 3-Inch to 8-Inch flange width, thickness up to 11/16-Inch Dual adjustment dials are fixed to trolley for precise alignment in 1/8-Inch increments