Engineered steel and heat treatment for maximum strength and flexibility. This Saxton 5pc Multi-Material Drill Bits Set features bits capable of cutting through very tough materials including Marble, Granite, Porcelain, Glass, Masonry and all types of wood. The set includes: (1x) 5mm x 98mm, (2x) 6mm x 102mm, (1x) 8mm x 118mm, (1x) 10mm x 120mm. They have hardened professional grade carbide tips for maximum strength and are suitable for all popular rawl plug sizes.