... use heat sensitive grain materials(organic chemical) which open electrical contacts when temperatures exceed the specified TF level.The ... blower ,microwave oven,refrigerator etc as heat protectionPass TUV,UL,PSE,EK, CCC SGS CertificationOrder InformationRYDXXX....XXX stand for ... 48460157RYD999970157RYD10410480157RYD1101109UL,TUV,PSE,EK certification