DYNAFORM 871090 - W-BEAM ISOFR GRAY 4X4 IN 1/4 IN TH 20 FT - W-BEAM WIDE FLANGE ISOPTHALIC POLYESTER FIRE-RETARDANT RESIN (ISOFR) DARK GRAY COLOR HEIGHT 4 IN WIDTH 4 IN THICKNESS 1/4 IN LENGTH 20 FT LENGTH TOLERANCE +/-0.125 IN MIN TEMP RATING -100 DEG F...