... With two rows of balls; WIB, BWF, WS, WK, 885000 series, etc. 2) Ball-roller: With one row of balls, one ... row of rollers; WIR, WN, WKH, 665000 series, etc. 2 Material: Mainly the chrome Steel (GCr15) High-chrome ... 58-62HBC, the hardness of ball and roller reaches 61-65 HRC, and the hardness of outer ring is 60-64HRC Application ... Widely used in auto, machine,etc Water pump bearing WB series