Review on AUTOOL 9PCS refrigerant oil checker analyzer tester for AC systems compatible with R134a/R1234yf refrigerants by Dan Quiceno

This is a brand new Chinese company, the proctor arrived with no instructions. The article was taped to the box, hiding the information. I use this product and don't see any color change even though the whole cartridge was clearly covered with oil. I contacted technical support and was unfamiliar with much of the terminology used. For example snow oil.