ZIRCONIA CERAMIC BEARING(SILICON NITRIDE BALL INSIDE AND PTFE CAGE) COLOR: WHITE TYPES: 604-6024,624-6224,634-6324,684-6824,694-6924,UC SERIES ETC. QUALITY: ABEC-1 ABEC-5 APPLICATION: HIGH TEMPERATURE (500 DEGREES C), HIGH HARDNESS, CORROSSION-RESISTANCE, SELF-LUBRICATION ETC.