Secure, no-slip connection: 6.35 mm (1/4-inch) hexagonal shank provides a stable, slip-resistant fit in standard drill chucks, reducing bit wobble and giving you precise control during plumbing tasks. Complete 6-piece set: Includes sizes 20 mm, 25 mm, 32 mm, 40 mm, 50 mm and 63 mm to cover common water pipe expansion and reaming needs — one set replaces multiple single-size tools. Fast, accurate pipe expansion: Spiral countersink drill bits with cutting edges rapidly open and ream pipe ends, cutting installation and repair time while producing clean, consistent results. Durable construction: Made from high-speed steel with a gold protective coating to retain sharpness, resist wear, and deliver reliable performance through repeated use. Simple to use: Fits into any 1/4-inch hex drill shank for quick bit changes and straightforward operation on-site or at home. Versatile for plumbing work: Designed specifically for water pipe expansion and reaming tasks; suitable for both professional plumbers and DIY projects. Typical applications: Reaming and expanding water pipe ends to prepare for couplings and fittings during repair or installation. Removing burrs and smoothing pipe interiors after cutting to ensure proper sealing and flow. On-site plumbing maintenance and emergency repairs where fast, reliable pipe prep is required. What you get: Six spiral countersink drill bits in sizes 20, 25, 32, 40, 50 and 63 mm with 6.35 mm (1/4-inch) hex shanks, high-speed steel construction and gold protective coating — a practical, durable solution for water pipe reaming and expansion.