Calling all perfectionists! Whether you're a professional engineer, meticulous woodworker, or just someone who wants things done right, this Groz engineering square is about to become your new best friend. That 4-inch steel blade has incredible accuracy with squareness of just 0.00063\ - yeah, that precise! It's perfect for setting up your table saw, band saw, jointer blades, miter saw, or any other tool where tight tolerances matter. The hardened spring steel blades are permanently fixed to the stock with those tapered self-locking rivets, which means complete rigidity and no wobble. What's really handy is that it has accurate right angles both inside and outside, giving you multiple ways to check your work. If you've ever struggled with tools that just aren't square enough, this little guy will save you so much frustration. It's one of those tools you didn't know you needed until you have it, and then you wonder how you ever managed without it!