Countersunk Post (Pin) Torx Self Tapping Screws create (taps) it's own thread as the screw is being driven in. They feature a small metal post (pin) in the middle of the screw head that prevents a normal Torx driver from engaging are used to protect and prevent unauthorised removal. These fasteners are extremely difficult to remove without a special tamper resistant Post Torx drive tool. The head is flat with a smooth tapered underside designed to sit flush in fittings with tapered recesses. Are also known as tamper resistance security screw they are used to protect and prevent unauthorised removal. Suitable for: Can you be used in stainless light gauge steel aluminium certain plastics and timber. To ensure the best result it is recommended to always drill a pilot hole Material / Coating: Stainless Steel A2-70 G304 is the most popular grade of stainless steel. It is aesthetically pleasing to the eye and very practical because of its excellent corrosion protection in most environments. Most products can be identified by the following markings: A2 A2-70 304 or G304. Stainless steels are largely non-magnetic but it is common for stainless steel fasteners to show a small degree of magnetism which is a result of work-hardening during the manufacturing process Can Stainless corrode?: Stainless steel is corrosion-resistant but not corrosion-proof and corrosion can occur if the material is installed or handled incorrectly. The use of tools and drills made from conventional steel during the installation of stainless steel fasteners may also lead to problems. Even the hardest of tools can produce debris that leaves minute steel particles on the stainless steel fastener surfaces or in pre-drilled holes. It is these particles that often rust when exposed to moisture or oxygen and can result in a stained or tarnished finish to the stainless steel material Fastener length: is generally measured from the point where the surface of the material will be when the fastener is installed to the end of the fastener. All material is advisory only and its use by anyone is entirely voluntary. Reliance on it for any purpose by anyone is at the sole risk of that person and Bolt and Nut Australia is not responsible for any loss claim or damages arising therefrom.