The Kinetic Research Group Hex Bit is an extended hex bit for Remington 700 and Tikka T3 action screws: This bit is useful when installing a Remington 700 or rifle that uses a metric M6 socket head (requiring 5mm hex wrench) such as a Tikka T3 into one of our chassis. It's also handy anywhere else you need to tighten a 1/4-28 or M6 socket head screw. The bit is a hex bit that is extra long and inserts into a common 1/4" drive like those that come on many firearms torque wrenches. For the Remington 700 bit, the round part of the bit is .235" in diameter, effective reach is about 1.75", total overall length is 2.75". For the Metric bit, the round part is also.235" (6mm), effective reach is about 2.84" (72mm) and overall length is 3.93" (100mm) FitsRemington: 1/4-28 socket head cap screws and other screws that require a 3/16" hexTikka: M6 socket head cap screws and other screws that require 5mm hex for metric version