12" Plastic T-Square Draw precise horizontal lines and measure with ease with the Helix Student Plastic T-Squares. These T-squares are made of lightweight, transparent plastic and feature easy-to-read inch and metric graduations. The head is designed to be placed at the edge of drafting tables, giving you incredible accuracy as you move your pen or pencil along the blade’s beveled edge to create straight horizontal lines. The T-squares also have a hang hole for easy storage.