These solid brass gauges clamp onto a carpenter's square to make repetitive angle marking easy.
Useful for laying out stair stringers, for roof framing, scarfing, etc. You can use any carpenter's framing square that has stock and tongue long enough to cover your tread:riser ratio.
About 1" high by 3/4" wide, with 3/16" jaw capacity.
There are two to a set.