A na-eji mgbanaka piston (Piston Ring) na-etinye eriri piston n'ime mgbanaka ọla, a na-ekewa piston mgbanaka n'ụdị abụọ: mgbanaka mkpakọ na mgbanaka mmanụ. Enwere ike iji mgbanaka mkpakọ mechie gas ngwakọta na-ere ọkụ n'ime ụlọ ọkụ; A na-eji mgbanaka mmanụ ehichapụ oke mmanụ na cylinder.
Mgbanaka piston bụ ụdị mgbanaka mgbanaka ọla nwere nnukwu nrụrụ mgbasawanye apụta, nke a na-agbakọta na profaịlụ na oghere anular kwekọrọ na ya. Mgbanaka piston na-atụgharị ma na-atụgharị na-adabere na ọdịiche nrụgide nke gas ma ọ bụ mmiri mmiri iji mepụta akara n'etiti gburugburu mpụta nke mgbanaka na cylinder na otu akụkụ nke mgbanaka na oghere mgbanaka.