CRAFTSMAN V20 Cordless Impact Wrench, 1/2 inch, Bare Tool Only (CMCF920B) - Amazon.com
Alternate - MSC Industrial Supply
1-1/2" Heavy Duty Air Impact Wrench (2500 ft.lb) - 1-1/2" Heavy Duty Pneumatic Impact Wrenches (2500 ft.lb), Air Impact Gun, Straight Air Torque Wrench, Air Wrench | Made in Taiwan Air tools
AVID POWER Cordless Impact Wrench, 1/2 Impact Gun w/Max Torque 330 ft lbs (450N.m), Power w/ 3.0A Li-ion Battery, 4 Pcs Impact Sockets and 1 Hour Fast Charger - Amazon.com