It's an inside mitre and try square, a depth gauge, a scribing tool for arcs and circles, a T-square, a depth marking scribe (excellent for marking out mortises), a plumb level, and a rule. Made of solid brass and steel, and carefully machined on all sides. Hardwood Rules are brass-bound and graduated in inches and metric units.
California residents: WARNING Proposition 65 notice
WARNING
This products can expose you to chemicals, including lead, which are known to the State of California to cause cancer and birth defects or other reproductive harm. For more information go to www.P65Warnings.ca.gov.