▁assembly ▁and ▁the ▁static ▁secondary ▁se aling ▁element . ▁ ▁The ▁m ating ▁ring ▁can ▁contain ▁the ▁se al ▁face ▁diam eters , ▁although ▁this ▁is ▁not ▁a ▁requirement ▁of ▁the ▁m ating ▁ring . ▁ ▁To ▁minim ize ▁primary ▁ring ▁motion , ▁the ▁m ating ▁ring ▁must ▁be ▁mounted ▁solid ly ▁and ▁should ▁form ▁a ▁per pend icular ▁plane ▁for ▁the ▁primary ▁ring ▁to ▁run ▁against . ▁ ▁Like ▁se al ▁rings , ▁m ating ▁rings ▁are ▁available ▁in ▁many ▁different ▁shapes . ▁ ▁Second ary ▁se aling ▁elements ▁ ▁Second ary ▁se aling ▁elements ▁are ▁g ask ets ▁which ▁provide ▁se aling ▁between ▁the ▁se al ▁ring ▁and ▁sh aft ▁( or ▁housing ) ▁and ▁the ▁m ating ▁ring ▁and ▁sh aft ▁( or ▁housing ). ▁ ▁Typ ical ▁secondary ▁se aling ▁elements ▁include ▁O - r ings , ▁wed ges ▁or ▁rub ber ▁dia ph rag ms . ▁The ▁secondary ▁se aling ▁elements ▁( there ▁may ▁be ▁a ▁number ▁of ▁them ) ▁are ▁not ▁rot ating ▁relative ▁to ▁one ▁another . ▁ ▁The ▁secondary ▁se aling ▁element ▁for ▁the ▁m ating ▁ring ▁is ▁always ▁static ▁ax ial ly ▁( although ▁it ▁may ▁be ▁rot ating ). ▁ ▁Second ary ▁se aling ▁elements ▁for ▁the ▁se al ▁ring ▁are ▁described ▁as ▁being ▁either ▁push er ▁or ▁non - push er ▁in ▁the ▁ax ial ▁direction . ▁The ▁term ▁push er ▁is ▁applied ▁to ▁secondary ▁se als ▁that ▁must ▁be ▁pushed ▁back ▁and ▁forth ▁by ▁the ▁movement ▁of ▁the ▁sh aft ▁or