Owned this for about a year now and absolutely amazing wrench. Was always sceptical about battery over air and stuck with my air compressor setup for years, moved a couple of years ago and garage has no power, plus a public footpath between house and garage means running permanent power would be a nightmare. So took the plunge and picked up the DCF899 with 2x5ah batteries and charger for £450. Much cheaper now seen screwfix do bare unit for £150. Did seem an expensive purchase but by time you add up cost of compressor, tools and ancillary bits it works out much cheaper than equivalent air options. As said was sceptical about how much power a battery operated wrench could actually put out and was totally converted first use, in fact I've undone vast majority of bolts on power setting 1 or 2 (out of 3). On paper it has 950nm of torque and 1650nm breakaway torque which is crazy figures. There are plenty of YouTube videos showing it shearing bolts (on purpose) and cracking lorry wheel nuts. It is quite a bulky unit but not much more bulky than an air wrench so working on cars can be a hassle at times finding space, on bikes though didn't find many bolts I couldn't get on with it. As for battery life, I've used it to take all 4 wheels off car a few times, all the front suspension off, for entire rebuild of ER5 and plenty of other small jobs inbetween and battery still shows full after initial charge!