About This Item. Quality Material - This drill is made of hard alloy, which is tough, tough and durable. Self-tapping drills can be screwed quickly and accurately without the need for tedious pre-drilling. No risk of cracks and crevices. Versatile- This bit will suit most drills and can be best tightened with electric hand drills to avoid climbing and slipping, especially for metals due to its harder. Largemutil - The drill kit is ideal for drilling on all materials, including tile, concrete, ceramic tile, bricks, wood, plastic, glass, masonry, etc. Remark: When drilling hard materials (glass, tile, marble or granite), lubricate with water. Big discounts - Each pack includes two different styles, one is a black triangle diamond and the other is an orange diamond. There are 10 pieces in total. The sizes are 6mm, 6mm, 8mm, 10mm, 12mm, which can meet your different needs. Service - If you have any questions, please feel free to contact us; we will get back to you within 24 hours. We will process your return or refund. See more details.