Compare this 1/4" Mini Air Die Grinder to the more expensive brands and you'll come to the same conclusion we did: ours is just as good, and an even better value! Features ball-bearing construction for long life, self-locking lever throttle, rear exhaust, and ergonomic grip. Stall-resistant design, with hardened gears and heat-treated components for durability and reliability. 1/4" FNPT air inlet