Torx (with pin) Tamper Proof Machine ScrewsCorrosion & Rust Resistant 18-8 Stainless Steel for Long Lasting ApplicationsCommonly Referred to as Star Drive or 6 Lobe Torx styled, star drive button head security machine screws in this selection have an added pin in the middle of the drive making it more secure. Only specific torx or star (with pin) bits will be able to easily remove these types of machine screws. These security screws are best for metal to metal application, used for securing materials from being tampered with such as in food prep and processing areas. You will often see security screws used in bathroom stalls and other public locations. The Star (with pin) drive style also deters stripping when installed correctly. Since the pressure on the head is more evenly distributed, higher torque can be applied without increased risk of stripping. Torx Button Head Tamper Proof Machine Screws Tamper Proof Drive Torx security screws feature a pin in the center of the drive which makes installation and removal of the screws very difficult (if not impossible) without a specially designed matching insert bit. This is designed to deter tampering and vandalism which makes this style of screw popular in public areas including bathroom stalls, gutters, license plates, grills in jails, schools, boats and cars. 18-8 Stainless Steel Security screws in this selection are all corrosion and rust resistant grade 18-8 stainless steel. Because of its durability, stainless steel is the perfect choice for tamper proof screws because they are suitable for long lasting, exterior applications or those exposed to the elements.