They're technically called ratcheting power wrenches, angle-head power wrenches or air-powered ratchets, but I call them knuckle- busters. Whatever their name, they're battery- or air-powered ratchet wrenches with a long handle at a right angle to a small, gear-driven drive head.
Because they're gear-driven, there's no "give" to them. When the nut or bolt stops turning, all the torque transfers immediately to the handle, whipping the user's hand into any nearby piece of metal or machinery. Hence the nickname, "knuckle buster."
I'm not fond of them, but there are times and places when they are the best tool for a repair. That's why I'm interested in new versions of that old design of tool that have appeared in the past few years.
Because I dislike being tethered to an air hose, I'm naturally interested in the new battery-powered versions of knuckle-buster power ratchet wrenches. Their enhanced portability is a big attraction for me, along with the buffering against knuckle-busting torque that battery-powered wrenches offer.
Equally interesting to me are the "impact" ratcheting wrenches that have been on the market for the past few years. Just as a conventional gun-style, air-powered impact wrench does't transfer much torque to the user when nuts or bolts stop turning, the hammer-style drive of these new air-powered impact-style ratchet wrenches greatly reduces their knuckle-busting tendencies.
I haven't had opportunity to "play" with either new design, but both are attractive to me. The deciding factor, along with price, will likely be which one has less probability of adding to the scars on my already battered knuckles.