Jewelry Maker's Square in Stainless Steel
I have used one of these for over 30 years, and have not seen them anywhere.
If you do not lose it, it will last you a lifetime.
Good for marking 90 degree angles, making square settings and square pieces, marking straight lines, etc.
I keep mine handy, and use it many times a week.
Many people drill a small hole in it and hang it on their bench.
It measures 32mm long, 21mm tall, and it is made out of 24 Gauge Stainless Steel (0.52mm)
These DO NOT have the JewelryMonk Logo on them. :(