Yellowhammer 38 inch Anodized Aluminum Straight Edge | Straight to within .002 over full 38" length machined flat and smooth reference edge, contoured cross section for easy gripping and hanging hole

I needed this flat bar, in conjunction with a few .003 and .004 feeler gauges to check the head and block surface on a '97 Miata 1.8 for flatness. This bar and the feeler gauges produced the exact same measurements as a machine shop that shaves heads for their primary work. Great tool to have just in case, and the price was great.

Well made product with dead on accuracy. It is built well with heavy gauge metal to prevent bending. I used this product for machinery setup such as my jointer to ensure co-planer measurements.

As some have mentioned the surface finish leaves something to be desired. One edge of mine was great and the other edge was a bit rough. The packing was a lot better than some of the other reviews indicated. Mine was packed in plastic with rubber end caps and then put in a heavy duty cardboard tube with end caps and then shipped in a cardboard box.

This product seems to be made in America which is fantastic for one but I checked it on a slab of boronsilicate glass and it is perfectly straight at room temperature it's made of aluminum so I don't know how well and how accurate it will be at high temperatures or low temperatures but at room temperature about 75°, it is absolutely flat not even my 1,000th feeler gauge can fit through it anywhere 10/10 fantastic product I bought it to measure the warpage on cylinder heads and it works good

Used on a 2014 Toyota Prius to check if the head was warped after a head leak. Not much could go wrong with a straight edge. Packed well. This is critical as you need it to be very accurate