Hei whakatau i te matotoru o te pakitara o ngā ngongo 3/16, me mōhio tātou ki te diameter o waho (OD) me te diameter o roto (ID) o te ngongo. Mena he 3/16″ te diameter o waho, ā, kāore he mōhiohio motuhake e whakaratohia ana mō te diameter o roto, kāore e taea te tatau tika i te matotoru o te pakitara. Ka rerekē pea te matotoru o te pakitara i runga i te momo ngongo me ngā paerewa hanga.