High Quality Formwork Drill Bit- Made of chrome vanadium steel (CR-V), these bit holders have very good abrasion resistance and extreme hardness for long service life. Essential drill and screwdriver accessory set.Easy assembly & Strong Magnetism- The magnetic screwdriver bit holder has a locking mechanism in the interfaces, with built-in strong magnet and automatic pop-up header for quick attachment which is essential in home and professional use. Permanent magnet holds bits securely in place, won\t get lost.Perfect connecting rod and amp; Length Extensions- 3 different lengths: 60mm, 100mm, 150mm, best fit your tools. Allows you to expand any type of hex shank bits and use screwdriver head conversion.Universal & Convenient- This bit holder set is a good tool accessory for conversion, suitable for universal 1/4" hex drill bits and screwdrivers.Wide Application- Suitable for DIY, professional, repairs and more.Indispensable for DIY and hobbies in the field of screws