10/7/14  Arrived within two days using "Prime" regular free delivery. Requires 2" bits, NOT 1" bits. Apply light pressure into wood or sheet rock or the clutch will not disengage ( deep hole results ). Always test on scrap before using first time - the adjustment collar will provide consistent, satisfactory results with your increased familiarity with this screwdriver. When screwed in to desired depth, unit chatters as though the bit is spinning on the screw head. It's OK, that's just the clutch releasing at the desired torque needed to sink the screw to the desired depth. Materials of different densities require different collar settings.