Starrett Square Head Only for 6" Combination Squares - Ideal for Woodworking and Metalworking - Black Wrinkle Finished, Cast Iron Steel Center Head - H11-6

Intended for use with the 6" long, 3/4" wide blade (ruler) made by Starrett. This would be a replacement head. Take care that you aren't getting this thinking you'll be using it with any ruler (blade). I had purchased the intended ruler thinking I could use it with my 4" double square. Unfortunately, the 4" and 6" rulers are a slightly different thickness. So I decided that rather than return the ruler, I would buy this smaller head and have a more portable combination square for the tool box. Glad I did.For those unfamiliar with Starrett squares, they are made in the USA, with outstanding quality materials and workmanship, and superb quality control. They are expensive, but they deserve to be. Starrett invented the combination square, and professionals still consider them to be among the best if not the very best made anywhere by anyone. The most common difference you'll notice between a quality square and cheap square is that cheap squares are often not actually square (not a true 90 degree angle). This is a real problem when you need precision.

Precision instrument.

It is advertised as a Starret. But mine is not. There is no Starret logo. It is a functional square. But not a Starret. Not reversible without removing the screw.