The 18-8 stainless steel thread cutting screw has a plain finish, a Type 25 point style, and a pan head with a star drive. The screw, also called a type BT thread cutting screw, has coarse threads and is suitable for use with plastics and other soft materials. The type 25 point tapers down to a blunt edge and directs chips out of the hole to prevent clogging. The large cutting surface enables screw installation with minimal rotating force. The 18-8 stainless steel material provides strength and offers good corrosion resistance in many environments. The material may be slightly magnetic. The pan head has a flat top and short vertical sides with a rounded top edge. The star drive, also called a Torx drive, has a six-pointed indentation that provides a large contact area for the driver, resisting slippage better than a Phillips or slotted drive. A star drive requires use of a Torx driver for installation and removal.
Thread cutting and thread rolling screws, two types of self-tapping screws, are threaded fasteners that create a mating thread in the wall of a hole. The two screws differ from each other in the way that they create the threads. Thread cutting screws cut the wall of the hole to create the thread, creating material chips that need to be cleared away from the hole to prevent clogging. Thread rolling screws, also called thread forming screws, do not remove material but instead press against the wall of the hole to displace the material and form the threads.