The Sew Steady More than 23" on Longest Side & Lip on Insert. Designed to fit your specific make and model of sewing machine and cabinet. Fills gaps around your sewing area. Made with one of the highest grades of acrylic. Inserts have a lip to catch on the cabinet top (as photo above illustrates) - this is when the cabinet opening has no method to support the insert. Insets (no lip) sit flush inside the cabinet opening & rest on a ledge built within the cabinet.