Quality generic screwdriver bit holders are made with high quality steel and are used throughout the aviation industry.With quality generic bit holders, you get economy and flexibility. Quality generic bit holders feature quality, select raw materials and only high grade tool steel. Each quality generic bit holder is manufactured to the tightest tolerances in the industry. Closer tolerances also mean a better fit and less cam-out or stripping, which in turn keeps work areas free of damage and reduces incidence of bit failure and costly re-work.MRO Extensions have hex tolerances that are on average 48% tighter than DIN and 35% tighter than ANSI requirements. With quality generic extensions you are assured of an exact, sure fit. All Quality generic extensions have the tightest tolerances for straightness and concentrically in the industry.