【3-Size Telescopic Design for Any Task】This adjustable magnetic drill bit holder set includes heavy-duty extensions that telescope from compact to long reach (approx. 3.1"-4.6", 4.7"-7.8", 5.5"-9.4"), covering virtually every screw-driving need. The design allows you to effortlessly reach deep, tight, or hard-to-access screws without changing tools. It’s the ultimate bit holder extension for precision drilling in confined spaces, ideal for projects, woodworking, and automotive repair. 【Strong Magnetic Locking & Wobble-Free Precision】Each magnetic bit holder is equipped with a powerful built-in magnet and a secure dual-locking interface that firmly holds both screwdriver bits and fastener heads. This magnetic locking mechanism eliminates bit slippage and reduces screw wobbling, ensuring perfect alignment, straight screw driving, and improved stability — even with long or heavy screws. 【One-Handed Control & Finger Protection】The independent outer sleeve lets the anti-slip rubber stay stationary while the inner shaft rotates. Hold the sleeve with one hand and operate the drill with the other for superior control. The self-retracting guide covers long screws, keeping them steady and protecting fingers. Ideal for tight spaces, overhead work, and precision fastening. 【Durable Galvanized Alloy Steel Construction】Crafted from industrial-grade galvanized alloy steel combined with hardened carbon steel, these heavy-duty bit extensions are built to withstand daily wear and resist rust or corrosion. The anti-slip comfort-grip rubber sleeve minimizes vibration and hand fatigue, offering excellent handling for extended use — perfect for professionals, electricians, mechanics, or home improvement users. 【Universal 1/4" Hex Shank Compatibility】Designed with a standard 1/4-inch hex shank, these magnetic drill bit extensions are compatible with most electric drills, cordless screwdrivers, and impact drivers. They fit all common screwdriver bits, drill bits, and socket adapters, making them ideal for furniture assembly, construction, automotive maintenance, and household repairs. A must-have adjustable magnetic screwdriver bit holder set for any toolbox.