A T-square is a technical drawing instrument that is primarily used as a guide for drawing horizontal lines on a drafting table. It is used by draftsmen. It is also used to guide the triangle that draws vertical lines. Its name comes from the general shape of the instrument where the horizontal member of the T slides on the side of the drafting table. Common lengths are 18", 24", 30", 36" and 42".| Catalog # | Description | EAN/UPC | Unit of Measure | Retail Price (2010) |
| 8387.18 | METAL T-SQUARE 18 INCH | 014173288929 | EA | - |
| 8387.24 | METAL T-SQUARE 24 INCH | 014173288936 | EA | - |
| 8387.36 | METAL T-SQUARE 36 INCH | 014173288950 | EA | - |
| STS18 | "STAINLESS STEEL T-SQUARE 18""" | 014173151230 | EA | - |
| STS24 | "STAINLESS STEEL T-SQUARE 24""" | 014173151254 | EA | - |
| STS30 | "STAINLESS STEEL T-SQUARE 30""" | 014173151261 | EA | - |
| STS36 | "STAINLESS STEEL T-SQUARE 36""" | 014173151278 | EA | - |
| STS42 | "STAINLESS STEEL T-SQUARE 42""" | 014173151285 | EA | - |
| STS48 | "STAINLESS STEEL T-SQUARE 48""" | 014173151292 | EA | - |
| ATS112 | "ALUMINUM SCHOLASTIC T-SQUARE 12""" | 014173148599 | EA | - |
| ATS115 | "ALUMINUM SCHOLASTIC T-SQUARE 15""" | 014173148605 | EA | - |
| ATS118 | "ALUMINUM SCHOLASTIC T-SQUARE 18""" | 014173148612 | EA | - |
| ATS124 | "ALUMINUM SCHOLASTIC T-SQUARE 24""" | 014173148629 | EA | - |
| ATS224 | "ALUMINUM PROFESSIONAL T-SQUARE 24""" | 014173148636 | EA | - |
| ATS230 | "ALUMINUM PROFESSIONAL T-SQUARE 30""" | 014173148643 | EA | - |
| ATS236 | "ALUMINUM PROFESSIONAL T-SQUARE 36""" | 014173148650 | EA | - |
| ATS242 | "ALUMINUM PROFESSIONAL T-SQUARE 42""" | 014173148667 | EA | - |
| ATS248 | "ALUMINUM PROFESSIONAL T-SQUARE 48""" | 014173148674 | EA | - |