إطار أو حاوية تفصل بين العناصر المتدحرجة للمحمل والكرة (كما تم تعديلها) وتحتفظ بها.
3.4347 cubic inches cubic measure, astm a108,11l41 to 11l44 assn std single material response or astm a304,41l40 assn std single material response or astm a505,4130 assn std single material response overall material document and classification, 1.8750 inches nominal bore diameter, 3.2500 inches nominal outside diameter, 0.7500 inches nominal overall width