6" Drill Bit Extension, Double Set Screw With Allen Wrench, Recommended For All 1/4" Round Shank Drill Bits Requiring Extra Reach, Follows 5/8" & Larger Bits Through Hole, 1/4" Shank, Pouched, Only Fits Round Shank Speedbor Bits, No. 88702, 6" & No. 88601, 12".