Rear handle trigger switch with no lock-on feature lock-off feature requires two actions to start the grinder redesigned motor with greater armature stability and larger commutator bars for 3 times longer life compared to previous model zig-zag epoxy on both sides of the armature coil and a powder-coated field for added protection from dust and debris for longer motor life labyrinth construction seals and protects the motor and bearings from dust and debris for longer tool life spiral bevel gears for smoother rotations and a more efficient transfer of energy aluminum gear housing provides superior gear alignment and smoother transmission for increased durability ac/dc switch for use with alternative power source side handle installs in three locations for operator comfort in various applications large spindle lock button for easier wheel changes while wearing gloves brush spiral spring allows for a 30% larger brush and increased air-flow compared to previous model automatic brush cut-off protects motor from damage for longer tool life brush door provides easy access to brushes for convenient replacement protects serial number identification label rubberized back handle for increased operator comfort compact design at 17-3/4 inch long and weighs 12. 1 Lbs. For added comfort includes 9 inch grinding guard and lock-nut wrenchgrinder switch type: rear trigger handle