This is a fine piece of equipment that allows you to assemble 10 frames at a time. It is adjustable so that you may assemble all 3 sizes. Place endbars between guides and run a bead of glue across them. Insert top bars and nail. Do the same for the bottom bars. Keeps frames square. End the frustration if you are going to assemble more than 50 frames at a time--this will save you time!