[DOUBLE LOCK] The drill bit extension features a locking mechanism at the interface, combined with slight magnetism at the bottom of the hole, ensuring the screwdriver bit or drill bit remains securely in place. This design helps reduce wobbling and prevents the bit from falling out. The locking mechanism on the magnetic bit holder allows for quick and easy bit changes, improving work efficiency. [PREMIUM QUALITY MATERIAL] The bit holder for impact driver is constructed from high-quality metal material, offering increased hardness and durability. This drill extension bit holder is compatible with most impact drivers and drill bit sets. [UNIVERSAL USE FOR 1/4 INCH] The quick-release bit holder is designed to work with most 1/4-inch blades or hex bits. The bit holder has a 1/4-inch hex shank, making this drill extension a must-have addition to your toolbox. [WIDE USE] The impact extension is compatible with electric screwdrivers, pneumatic screwdrivers, hand screwdrivers, T-handle 1/4-inch screwdrivers, corded drills, cordless drills, pneumatic drills, impact drills, and other tools with a 1/4-inch hex shank. The drill bit extender is ideal for maintenance, repairs, and DIY projects in automotive, hardware, home improvement, and other applications. [PACKAGE CONTENT] Includes 4 locking bit holders in 4 different lengths: 2 inches (60 mm), 4 inches (100 mm), 6 inches (150 mm), and 12 inches (295 mm). Whether for simple tasks or complex jobs, this magnetic drill bit holder set provides the right tool for various situations. Color: Black & Red Material: Metal Package Contents: 4 x Drill Bit Extension Note: Light reflection and different display settings may cause slight color variations between the image and the actual item. Measurement may vary by +/- 1-3 cm.