Ko te riipene taha-rua he mea hanga ki te pepa, ki te kakahu, ki te kiriata kirihou hei tïpako, katahi ka whakakikoruatia ki runga i te tïpako i runga i te tïpako i runga ake nei te momo elastomer pehanga-tairongo apiti ranei.E toru nga wahanga o te riipene whakapiri-ahua: tïpako, whakapiri me te pepa tuku (kiriata).