Hercules Stretcher Bars are museum quality, top of the line stretcher bars of exceptional strength and stability. They consist of precision dimensioned Aspen wood inserts mated to close tolerance aluminum profiles, eliminating the possibility of warping, twisting, or bending. They are so strong, in fact, that no cross bars or keys are ever required Their aluminum alloy profiles offer incredible structural integrity and their aspen inserts are ideal for retaining staples, tacks, and nails. The wood insert face is raised 116 in. above the aluminum for easy canvas fastening, and all corners are gently curved for frameless wrapping. The bars also feature specially designed rolled top edges that ensure a consistently tight canvas fit. The edges suspend the painting surface above the bar rack without creating unwanted impressions. Hercules Stretcher Bars have super strong steel inserts with special bosses. Necessary for assembly, these inserts allow you to put frames together in 90 seconds. Simply tap together for a permanent press fit. One hanging bracket is included with each pair. Hercules Stretcher Bars are sold and packaged in pairs. Bars are 1 12 in. wide x 1 in. deep and available in various lengths. Length measurement is for the outside long side of the stretcher bar. Larger sizes must be shipped via freight shipment, therefore the shipping rates are higher. Made in the USA.