Comparison : Item # TR640.101.240A, 6 x 4 x 1/4 Inch (in) Size Isophthalic Polyester (I) Rectangular Box Fiberglass Beam
Item # TR640.286.240A, 6 x 4 x 1/4 Inch (in) Size Isophthalic Fire Retardant (IFR) Rectangular Box Fiberglass Beam
Item # TR640.303.240A, 6 x 4 x 1/4 Inch (in) Size Vinyl Ester Fire Retardant (VFR) Rectangular Box Fiberglass Beam
Item # TR740.101.240A, 7 x 4 x 1/4 Inch (in) Size Isophthalic Polyester (I) Rectangular Box Fiberglass Beam
Item # TR740.286.240A, 7 x 4 x 1/4 Inch (in) Size Isophthalic Fire Retardant (IFR) Rectangular Box Fiberglass Beam