Alvin Paral-Liner and Paral-Liner Deluxe parallel drafting straightedges features integral comfort grip bar to control straightedge movement. Constructed of rigid black phenolic plastic; resists perspiration stains and corrosion. Floating roller movement allows the user to move the straightedge with minimal effort and then lock it in place. Mobile straightedge affords frictionless operation through the floating action of the nylon rollers mounted on the blade. The rollers retract at a touch, securing the blade for accurate drawing. Clear acrylic plastic edges are elevated to prevent ink smears and steel ball-bearing pulleys provide smooth movement. Includes all mounting hardware and installation instructions.