Steel-reinforced collar Enhances durability and protects tool when dropped on the chuck. Unibody powertrain Maintains alignment between clutch, gearbox and motor for the most durable drivetrain system on the market. DuraShield™ housing Constructed to withstand real world conditions. Highest Torque available Powers through the toughest applications with 550 in.-lbs. of torque. Two-speed gearbox 0-400/0-1,300 RPM. Externally changeable brushes Can be replaced in as little as 2 minutes. Ratcheting, single-sleeve 1/2″ chuck with carbide teeth For one-handed operation and stronger bit grip