Click to expand Tap to zoom T-Square Ruler by Westcott Sold out $6.00 1 2 3 4 5 6 7 8 9 10+ Quantity Quantity Sold out C-THRU RULER CO-T-Square: 12in. This specialized drawing instrument allows you to draw straight horizontal lines with ease. This package contains one 12in T-square (total measurements are 13x6in). Made of durable clear plastic. Imported.