These braces are specifically constructed to work with Masterpiece's Elite Heavy Duty Stretcher Bars. Select straight braces by the short frame dimension. For example, the 48" brace would be used with a 48" x 72" canvas frame. Straight braces are 3.25" wide. These stretcher bars have a patented groove on the inside of the bar that accepts this particular brace. The straight braces slide into the groove and are offset from the stretcher bar forming a slot. There is a long slender key that can be inserted into the slot on the stretcher bar making the brace key-able. No cutting or woodworking is required, only a simple rubber mallet is needed for assembly. These braces also feature a groove running on either edge of the brace that will accept cross braces. When used together Elite straight braces, cross braces and stretcher bars produce a very strong, solid-wood, key-able, professional, museum quality braced canvas frame.