He pai rawa ngā peera roera porotaka kotahi te rarangi hei kawe i ngā kaha radial teitei. I runga i te hoahoa, i te whakatakotoranga rānei o ngā pakihiwi, ka taea e ngā peera roera porotaka te tu atu i ngā kaha axial iti i te taha kotahi, i ngā taha e rua rānei. Ko ngā peera roera porotaka kotahi te rarangi he peera ka taea te tango – kia māmā ake ai te huihui, te wetewete rānei i te peera.
