Using the BEST Medium-Duty Stretcher Bar - 20" gives the artist a smoothly stretched canvas that is free of ghost impressions. This is accomplished by the back edge which is rounded. It helps to reduce friction, allowing the canvas to remain 1/2 inch from the stretcher bar itself. Designed of knot free white pine that has been kiln dried, this stretcher bar is 1 1/2" high and 1 1/4" deep. The 20 inch length gives the discerning artist plenty of room to work while also allowing for easy portability between home and the studio.