The Fix It Sticks Extended Action Bit has a custom ball end hex bit designed to tighten hard to reach screws. Works with any standard 1/4" bit driver. The shaft of the bit is 0.1875" x 4" long for hard to reach screws. Notes:Choose 3/16" for Remington 700, AICS, etc.Choose 5/32" for Ruger 10/22 V-Block, etc.Choose 5/64" for general useChoose 1/8" for KIDD, etc.Choose 5mm for Action ScrewsChoose T30 for numerous Precision Rifles (T30 is not a Ball End)Shaft of bit is 0.1875" X 4.0" long for hard to reach screws.Works with any standard 1/4" bit driver