The Impact-Rated 41-Piece Screwdriver / Nut Driver Set is part of Klein's KNECT™ system. KNECT™ is a cross compatible impact-rated driver and ratchet system that delivers a seamless back and forth transition between hand and power tools. Houses popular screwdriver tips, nut driver sizes and deep well impact sockets. It's the familiar feel of a multi-bit screwdriver set, with the added utility to complete any job. Case clips to other Klein cases and the MODbox™ case adapter side rail attachment.