The 5" Incra Guaranteed Square is an innovative one-piece design using the most advanced manufacturing methods to fabricate a single, monolithic blade/handle body from a solid slab of hardened aluminum. anodized for a durable, beautiful surface. An unique feature of this square is the support lip which holds the tool on the edge of the work-piece helping to avoid a possible trip to the floor. Blade size: height (heel to toe) is 5½˝, width is 1˝, thickness is ¼˝. Base size: length is 5«˝, width is1«˝ and thickness is ¾˝. Incra's Certificate of Accuracy guarantees the maximum deviation form nominal at any point along the full length of the blade to more than 0.001˝.