This set of Four engineer's squares brings a high level of precision to every task. 2", 3", 4" and 6" squares let you choose the ideal size for every job: marking stock for careful joinery, checking tools for sharpening, verifying accurate assembly or making sure your tablesaw blade is set up perfectly. Hardened spring steel blades are fixed to the stock with self-locking tapered rivets to insure permanent accuracy. These all-steel squares are precision ground and tempered as described above. The case is a softwood and plywood construction. These cases are and very stable and do not warp.