Features Wide range of applications: The cutting head base cordless screwdrivers are suitable for extending different screwdriver heads and drill bits. Can be installed on a variety of tools, such as impact wrench, electric screwdriver, manual screwdriver, electric drill, gas drill, etc. Convenient installation: When installing, simply press the red sleeve of the quick change BIT base, and the Hexagon of the quick-change BIT base is exposed; The drill is then inserted into the hex head, and the magnetic holder of the drill bit can automatically tighten the drill. High quality materials: high carbon steel bracket for maximum durability, sturdy construction for extended service life, high strength and wear resistance, not easy to break or damage. Aluminum alloy sleeves are corrosion resistant and not rusty, which can better protect the drill bit from corrosion. Special note: this magnetic drill seat can only be installed using a single head screwdriver and not a double head screwdriver. The universal 1/4 inch hex handle and the 1/4 inch hex socket are suitable for most electric screwdrivers, hand screwdrivers, and drill bits Bit holders have strong magnetism, can be connected or disconnected quickly and are held in position while driving; The small size allows you to extend the drill bit anywhere for any job and fits many tool bags; It is useful to remove or tighten a large amount of screws after starting or loosening Product Features: External & Internal Measuring Jaw Locking Screw Large LCD Display Linear Capacitive Measuring System Depth Measuring Blade Zero Setting at any point Stepped Measuring Faces Easy to change battery. Hard Plastic Case Hardened Stainless Steel 0 to 300 mm measuring range 0.01mm Resolution 0.02 mm/0.001 Inch Accuracy up to 100 mm 0.03 mm/0.001 Inch Accuracy 100 to 300 mm which is very easy to hold and use，Strong hardness, not easy to wear, durable to use. Suitable for high frequency circuit adjustment. Fit for various inductance, semi variable capacitor, half electric resistance We support our best service, high quality 4Pcs Slotted Screwdriver Set , if you have any questions about our Adjust Frequency Screwdriver, please do not hesitate to contact us, we will try our best to help you and reply within 24 hours. Package Includes: 1 x 300mm Digital Vernier Caliper User Manual Note: LCD Display will work as soon as you slide Caliper.It's not product quality problem.Hope you can understand! Package List