1. High-Performance Drilling: The 3PCS external cooling carbide drill bit set features a non-standard diameter of 3.00, 4.0, and 5.0 mm, ensuring exceptional performance for various drilling tasks.(3x14x50xD4 4x18x50xD4 5x20x50xD5) 2. Durable Solid Tungsten Construction: Crafted from solid tungsten, these drill bits offer superior durability and longevity, making them ideal for both professional and DIY applications. 3. Effective Cooling System: Designed with an internal cooling mechanism, these carbide drill bits maintain optimal temperature during use, enhancing cutting efficiency and prolonging tool life. 4. Versatile Application: Perfect for drilling into a variety of materials, the 3PCS external cooling carbide drill bit set is suitable for metal, wood, and plastic, providing versatility for all your projects. 5. Precision Engineering: Each drill bit in this set is engineered for precision, allowing for clean and accurate holes, essential for any high-quality work involving non-standard diameters. Colour:As Shown Material:tungsten steel Package Contents: 3 * external cooling carbide drill bit Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.