The Irwin Tools 4935705 Speedbor 1/4-Inch Lock N’ Load Quick Change Bit Holder 12-Inch Over All Length has a Carbon steel construction sleeve and body for durability and life. The Lock-n-Load system is designed for one-handed quick release to get the job done quicker. The Patented jaw design holds bits securely on 6-flatted shanks, as well as ball detent bits. The 1/4-Inch Quick Change range now holds insert bits and uses magnets for holding the bits. The 1/4-Inch Lock N’ Load exntension can be use for Speedbor Blue Groove Bits All Sizes, Speedbor Max Speed Sizes 7/16-Inch to 1-1/4-Inch, Fastener Drive All products, UNIBIT Sizes #1, #2, #10, #12, 1/4 Hole Saw Arbor Sizes 9/16-Inch to 1-3/16-Inch, and Countersinks Sizes #4 to #12.