The female thread gas regulator, known as the 'gold top' is threaded on the inside so the gas bottle it fits is one that is threaded outside. MALE THREAD IS SENT AS STANDARD, specification is needed when placing your order if it is female thread that you need. If you have any other quieries do not hesitate to call us, although both regulator and bottle threads are shown in photographs below to try help you differentiate if this is the regulator you need.