Bit Holder Set: You will receive 4 pieces magnetic extension chuck adapters, the length is 60mm. The mini hex shank screwdriver bit holder can be easily inserted into electric screwdriver, drill and handheld screwdriver, enough quantity to meet your daily use and replacement needs. Durable Material: The drill bit extension set is made of high quality carbon steel, high hardness, sturdy and durable, wear-resistant and corrosion-resistant. Sturdy construction allows for a long service life. Strong Magnetism: Our drill bit extension has a powerful built-in magnet, firmly absorbs the bits and does not fall off, ensures that the screwdriver bits stay in place stably. It can be quickly connected or disconnected and allows easy one-handed bit tip changes. Self-Locking Design: Quick release system design, batch head automatically open, press the knurled part for quick release. It can help you quickly install and change the screwdriver bit. Simple operation, quick fixation, greatly improving