Feature: 1. Adjustable Counterbore: Adjustable length of the counterborn,with fixing screw,use the attached hex key remove the screw and adjust the length of the counterbore. 2. Premium Quality: The drill bit made of steel alloy,more hardness,provide fast cutting and strong force. 3. Efficient Work: Smooth counterbore drilled to save you time and labor. The surface of the workpiece will be perfectly embedded with screw cap. 4. Compatible with: Applied with drilling rig,bench drill,hand drill and charging drill. 5. Use Tip: Vertical to avoid the drill bit from bending or breaking. Specification: Features: Adjustable Counterbore: Adjustable length of the counterborn,with fixing screw,use the attached hex key remove the screw and adjust the length of the counterbore. Premium Quality: The drill bit made of steel alloy,more hardness,provide fast cutting and strong force. Efficient Work: Smooth counterbore drilled to save you time and labor. The surface of the workpiece will be perfectly embedded with screw cap. Compatible with: Applied with drilling rig,bench drill,hand drill and charging drill. Use Tip: Vertical to avoid the drill bit from bending or breaking. Specifications: Material: Steel Alloy Size: 8*2.8, 8*3, 8*3.2, 8*3.5, 8*4mm Item Weight: 98g / 3.46oz Package Weight: 107g / 3.77oz Package Size: 100*50*50mm / 3.94*1.97*1.97in Package List: 5 * Drill Bit 5 * Hex Key Package List: 5 * Drill Bit 5 * Hex Key