實心或空心結構的圓柱體,為滾子軸承提供滾動元件。
sae-j770 assn std single material response overall material document and classification, 0.1248 inches minimum and 0.1250 inches maximum overall length, steel comp e52100 overall material, 0.1248 inches minimum and 0.1250 inches maximum rolling element diameter, needle roller, ball ends style designator