Those are Carpenter’s Try Squares / L-Squares
What they are:
• Type: Try square / Engineer’s square with ruler
• Blade: Yellow ACCAIO TEMPERATO = "Tempered Steel". 25cm / 250mm long
• Stock: Black metal handle, looks cast aluminum
• Markings: Metric in cm + mm. Also says G.HARTER STAHL = German hardened steel
What they’re used for:
This is a layout and checking tool for woodworking, metalwork, and construction.
1. Check 90° angles - make sure corners are square
2. Mark straight lines - run a pencil along the blade
3. Measure - the blade is a ruler up to 25cm
4. Check flatness - lay the stock against an edge to see if it’s true