S129 Magnetic Bit Holders Bulk Magnetic bit holders are suitable for 25mm insert bits and help you change bits faster for greater productivity. Hex opening: designed to fit all 1/4" hex insert bits Rare earth magnet is 4 times stronger than standard magnets C-Ring internal clip fits into the retaining notch of insert bits to hold the bit securely in place 1/4" hex shank with power groove for use in power tools and quick change adapters Tough grade high-alloy Chrome Vanadium steel absorbs shock and offers superior performance