Museo Alu-Frame Aluminum Stretcher Bars feature a reinforced structure comprised of wear-resistant aluminum and sturdy wood for maximum stability. Unlike all-wood stretcher bars, aluminum bars are unaffected by changes in humidity and temperature. They won't twist, bend, or warp. - MUSEO ALU-Frame Aluminum Stretcher Bars and Parts - Heavy Duty Hangers, Pkg of 2Museo Aluminum Stretch Bar, SET 3 - For optimum suspension, these hangers are recommended when hanging works larger than 72" × 72" as well as 60" × 80" or 48" × 96" frames. Sold in a pack of two.