PTFE tape is typically for use with low pressure, non-critical applications in sizes up to 1". PTFE tape is not a reliable thread sealant and should not be used in most applications. The N121-050/075 are 0.0030 thick and the GAS-YT70 is yellow in colour (UL Gas) and can be used as a premium industrial tape. Grey GAS-SA26 contains an anti-galling agent that is ideal for difficult service conditions associated with stainless steel, aluminum & brass threaded connections, whereas, the Green GAS-GT90 is made from an oil-free PTFE formula designed for oxygen service applications and the Pink GAS-PT80 is a triple density, high temperature tape designed for hot water & steam applications.