Ināianei, he maha ngā huarahi rerekē hei horoi i ngā oko karaihe i roto i te taiwhanga, arā, te horoi ā-ringa, te horoi ultrasonic, te mīhini horoi ā-haurua-aunoa, me te mīhini horoi karaihe aunoa. Heoi anō, ko te ma o te horoinga te mea e whakatau ana i te tika o te whakamātautau e whai ake nei, tae atu ki te angitu o te whakamātautau. Ka whakarāpopototia e te ētita ētahi āhuatanga nui e pā ana ki te horoi, ā, ka whakarāpopototia kia rima ngā tohu CTWMT:

C：Matū
E ai ki te kaupapa o te rauemi horoi, whiriwhiria ngā wāhanga rerekē o te hopi horoi

T：Te pāmahana 
Ko te tikanga, ka pai ake te hua o te horoinga ina teitei ake te pāmahana horoi.

W：Kounga Wai
Ko te wai te mea matua i roto i te tukanga horoi, engari he rerekē te kounga o te wai i ia wāhi, nō reira kāore e taea te kī taurangi te hua o te horoinga.

M：Te kaha miihini
Ka tangohia te toenga mai i te mata o te oko e ngā kaha o waho

T：Wā
Mena he ōrite ngā mea katoa, ko te tikanga, ko te roa o te wā horoi ka pai ake te hua horoi.

Ko te kaupapa o te horoi karāhe aunoa: te whakamahana i te wai, te tāpiri i te hopi motuhake mā te papu tohanga ki roto i te paipa kete ngaio me te pēhanga iti me te tohanga teitei hei horoi i te mata o roto o ngā karāhe. Ko ngā ringa rehu o runga me raro ka horoi i te mata o waho o ngā karāhe. Me te wā me ngā mahi horoi pūtaiao, kia tutuki ai te kaupapa o te horoi i ngā karāhe.