Super strong rare earth magnets for ultimate holding power. 9" solid aluminum billet provides the highest structural strength available. 3 vial lighted system improves readability in low light settings. 10 minute automatic shut Off turns the lighted vials Off after a 10 minute continuous run time to save the life of batteries. Laser engraved SAE and metric measurements. Accurate to .019 deg. or .0005". Precision machined edges provide maximum accuracy. Large, relaxed V-groove for working with round corners or material up to 10" in diameter.