A rugged, cast iron square head that will outlast cheap plastic and die-cast imitations. An accurate, hardened and tempered square blade offered in inch, millimeter, and inch and millimeter combined. Reversible lock bolt allows the blade to be turned over or end-for-end so that all four graduated edges may be used. The combination square can be used as a try square, 45° miter, a depth gage, a height gage, a layout tool, and as a rule. An optional center head is available to increase the versatility of this universal measuring tool. 4 graduated edges. For training "youngsters" and apprentices to lay out and check their work more efficiently.