Wutan madaurin kai na Flex suna da kawukan da ke jujjuyawa a cikin abin motsawa don ba da damar yin amfani da mashin ɗin a kusurwoyi daban-daban, yana ƙara isa ga mashin ɗin.
Ana yin motsi daga tushe na kai ko ƙarshen shaft. Ƙaƙwalwa a ƙarshen ramin yana ba da damar kai don samun bayanan martaba guda biyu.
Duk nau'ikan kawunan maƙarƙashiya na iya zama na ƙirar kai mai sassauƙa. Ɗaya daga cikin ƙirar ƙira na yau da kullun shine haɗin kai tare da kafaffen kai mai buɗewa da kan zoben ratchet mai sassauƙa (duba hoto). Menene maɓalli na haɗin gwiwa?).
Har ila yau, maƙallan kai da soket suna gama gari. Socket soket sun yi kama da maƙallan akwatin kuma sun dace da saman kan na'urar don rufe shi gaba ɗaya yayin amfani. Wrenches masu tsinkewa misali ne na madaukakan soket na kai (saffolding wrenches)Dubi Menene Wurin Wuta?).
