Phillips Flat Head High Low Thread Forming Screws for Brittle Plastic
Alternating high and low threads minimize cracking and splitting in brittle material such as phenolic and glass-filled plastic.
A thread forming screw with a double-lead, consisting of a high and low thread. The lower thread varies in height from 1/3 to 1/2 that of the higher thread, which is sharper and flatter than a standard thread. 18-8 stainless steel (SUS304) screws have good chemical resistance and may be mildly magnetic. 410 stainless steel screws are stronger and more wear resistant than 18-8 stainless steel screws, these are magnetic and mildly chemical resistant. Steel screws are zinc plated to protect the steel from corroding in wet environments. Black zinc-plated screws blend in with dark surfaces and reduce glare.