PREMIUM S2 STEEL: Ball end hex bits are made of S2 steel material, ball end allen bit set be black phosphating treatment by surface for good anti-rust, more stronger and durable than others KINDLY TIPS: Due to low torque, ball end hex bits are more great for 1/4'' hex shank manual screwdriver; not well for power drill because low torque would lead to the ball end part easy to be rounded over, we strongly recommend that using it on manual tools for the best results PERFECT SIZES: 24PCS 2.5 inch long ball end hex head allen wrench drill bits including 12PCS SAE of 1/16" 5/64", 3/32", 7/64", 1/8", 9/64", 5/32", 3/16", 7/32", 1/4", 5/16", 3/8" and 12PCS Metric of 2mm, 2.5mm, 3mm, 3.5mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, 12mm BALL END DESIGN: Can tighten the screw in vertical or inclined side, suitable for limited space. Ball End hex bits built-in magnetic, can be easily keep screws stuck to them. All the ball end hex bit set packed in a plastic screwdriver holder storage bar, for convenient to store and carry QUICK CHANGE BIT DRIVER: Come with a quick release screwdriver bit driver handle, perfect for all kinds of hex shank screwdriver bits, the quick-release chuck enables rapid bit change without needing any special tools. Using these ball end hex bit set with screwdriver bit driver handle, make assembling furniture in an easy way Ball End Hex Bit Set