These digital protractors allow you to precisely set angles in 0.05 degree increments. All protractors have strong magnets on all four edge surfaces and a front locking lever to hold the arm position while transferring measurements. Each protractor now features a hold function, ensuring you never loose your reading and a reverse reading capability for those hard to calculate angles. The smaller protractor, measuring 4″ from pivot to end, works great to set miter gauges, bandsaws, drill presses, etc. while the larger models, measuring 8″ and 12″ from pivot to end, work well on miter saws, door frames and wall angles for cutting crown molding and trim.