Design: Strong tungsten carbide tip easily penetrates various materials, U-groove drill bit design, surface rust treatment, smoother drilling and chip removal. Application: Strong tungsten carbide tip can easily penetrate various materials (tile, concrete, brick wall, glass, mirrors, plastic masonry and wood). Sturdy: High quality multi-purpose drill bit set made of tungsten carbide material which prevents the drill bit from cracking and provides a longer service life, sturdy and durable. Assorted sizes: 10pcs drill bits in 4 different sizes, 4 x 6mm, 2 x 8mm, 2 x 10mm, 2 x 12mm, different sizes for different use to help you finish your daily needs. Tips: When drilling hard materials (glass, porcelain tiles, marble or granite), please use water for lubrication Quantity: 10 pieces Blue color