I ordered the Milescraft Exactor from Amazon.com ($8.79 + tax, delivered).
It arrived in an obscenely difficult to open blister pack.
I checked it for accuracy. I measured the width of the body at four spots using a dial vernier caliper and found that it was perfectly uniform.
I also used the calipers to check the ruler at 1", 2", 3", 4", and 5" and found that to be accurate.
This morning I gave it to our QC manager to check the accuracy of 90 degree and 45 degree angle settings using our Nikon optical comparator (calibrated each year).
The 90 degree was perfectly on. The 45 degree angle was off by 9 minutes (just under one degree). Surprisingly there was no wobble at all on the angle settings.
I don't have a quantitative way to check the accuracy of the level bubbles, other than they seem just about the same as my good aluminum torpedo level.
The bubble levels are hard to see from the ruler side of the piece, but not too bad from the rear. But it is difficult to see from an angle. If I remove the thumbscrew I can lay it down flat and easily see the both vials and check for level in two directions.
Of all the squares I have (and I have several) this is the one that is most likely to remain in my pocket.
I like the depth function; it is a bit easier to use than the one on my vernier caliper.
It does not feel like junk, but it does not feel particularly like a precision measuring device. To do that they would have had to machine the body out of aluminum instead of molding it from resin. But a fair compromise. I think it is accurate enough for woodworking.
