5Pcs Quick Change Adjustable Countersink Drill Bit Set, 8Mm Round Shank 2.8-4Mm Main Features: Specifications. Woodworking countersink drill bit set for wood screws without changing bits. Drilling length can be adjusted for various length screws simply by loosening and tightening the setscrew. Parameters. 8mm round shank countersink drill bit set included 5 kinds of sizes: 2.8 x 8mm, 3.0 x 8mm, 3.2 x 8mm, 3.5 x 8mm, 4.0 x 8mm bits, very suitable for drilling holes, opening range is 2.8-4mm, and adjustable cutting height: 2.5-10.5mm. Suitable for drilling machines with chucks such as electric drills, hand drills, bench drills, etc. Provides precise, clean pilot holes in compressed board, plastic, MDF, pine and more. Perfect for woodworkers, DIY enthusiasts, home repairs and more. High Quality. Made of 45# steel, carbide tip: YG8, durable and corrosion resistant. Good toughness, wear resistance, strong drilling capacity. Premium Quality Service. All our products are extensively tested to comply with rigorous and strict QC standards. We offer a 60-day refund guarantee.