Credit and Quality Main Seals Type OPEN, ZZ, 2RS, RS, Z, NR,etc Main Material GCR15, Carbon Steel, Stainless Steel, Ceramic, etc Main Ball Material GCR15, Carbon Steel, Stainless Steel, Ceramic, etc Main Cage Material Metal, Plastic Tolerances P0 ( ABEC1 ), P6 ( ABEC-3 ), P5 ( ABEC-5 ), P4 ( ABEC-7 ), P2 ( ABEC-9 ), etc Clearances C2, Cn (..