Aluminum alloy frame, channel, strip, pads and mesh guard welded construction, enamel olive drab finish, 2-5/8 in. W by 44-1/4 in. Lg by 3-1/4 in. H, four 1/4 in.-20 unc 2b thd mtg holes and four 0.265 to 0.336 in. Diameter mtg holes spaced 13-1/4 in. C to c on opposite sides along the lg