Magnetic Centering Head with Vial, 6 in and Larger Pipe Capacity, Medium no checkout Designed for more comfort and Designed for more comfort and better fit with lighter Durable nylon frame with 5 position ratcheting temple design for optimum fit Non slip TPR temples for comfort and grip Over the glass designed to fit over prescription eyewear One piece Y shaped body design with magnetic legs Built in dial with 2 1 2° increments that turns 360° Hardened center punch marks set position by taping with a hammer Used to establish and mark a centerline at any angle around circumference on a pipe or tank or as a protractor level Excessive heat can damage magnets