There is a commercial version of this tool that you can't find easily in stores. In fact it's hard to find online a bit. Runs about 200-270 new with the case, 2 batteries and a charger. I've got one and it's exactly like a real impact gun. Lets see if i can dig up the model.
It's a full size 1/2" drive.

Found it, Here it is:


•Frameless motor for extended tool durability and life
•Compact size and weight allow access into tighter areas and reduces user fatigue
•1,740 in-lbs of torque to perform a wide range of fastening applications
•0-2,400 rpm/0-2,700 ipm for faster application speed
•Replaceable brushes for increased serviceability
•Textured anti-slip comfort grip provides maximum comfort
•Durable magnesium gear case and all metal transmission for extended durability
•Heavy-duty impacting mechanism directs torque to fastener without kickback