A nail is a glass accessory used for vaporizing plant extract. All nails feature a long, thin stem capped with a flat dish. Vapor is produced by superheating the nail with a torch and applying plant extract to the top of the dish. First generation nail designs fit inside standardized female joints and require a glass dome to prevent the vapor from escaping. GRAV® nails are domeless and feature a hollow center and a raised lip around the dish. GRAV® nails are made from quartz, the purest silicate type of glass and one of the few types more heat-tolerant than borosilicate. Quartz allows the nails to be heated to the extreme temperatures needed to vaporize plant extract on contact.