Patent ID: 7954660

Claim:
A plastic gas cap comprising: a cap element having a plastic skirt, said plastic skirt having an inner skirt diameter and including ring retaining means extending inwardly from said inner skirt diameter; a plug element having a flange at one end sized and shaped to fit within said plastic skirt past said ring retaining means; a plastic retaining ring having an outer ring diameter, said plastic retaining ring being secured between said flange and said inwardly directed ring retaining means to secure said plug element in said cap element, wherein said plastic retaining ring is made from glass reinforced plastic wherein said outer ring diameter is sized and shaped to form an interference fit within said inner skirt diameter to reinforce said plastic skirt; wherein said flange includes engaging means for permitting said flange to slip within said gas cap in the tightening direction, but not in the untightening direction; and wherein said engaging means comprise teeth oriented to engage in slots formed into the gas cap.