Ingilazi evikelayo, eyaziwa nangokuthi ingilazi enezingqimba ezimbili, iyasebenza odongeni lwangaphandle lwezakhiwo.Ibhekisela ohlelweni lwesakhiwo sokusekela esinekhono elithile lokuguquguquka uma kuqhathaniswa nesakhiwo esiyinhloko, kodwa uhlelo lwesakhiwo sengilazi aluhlanganyeli isisindo noma isakhiwo somthwalo wesakhiwo kanye nomzimba oyinhloko.Kuwudonga lwesakhiwo, olwenziwa ngokuyinhloko ngengilazi enezingqimba ezimbili ene-insulation kanye ne-sound insulation