Raumer’s proprietary “spit” bolt. All 316L stainless steel. The surface of expanding end has cross-knurling, which makes it very resistance to extraction. This is not a self drilling anchor; however, unlike a classic Spit bolt, the hole can be drilled to a final depth with a carbide drill bit. The cone is attached to the anchor at the factory, no more dropping or swallowing cones. Installation instructions