The norm is to get a standard CO2 regulator from the likes of a welding supply shop & then get a step down connector to allow the your hose to be fitted to the regulator.
I don't know what the convention is where you are, but in the UK & Europe CO2 regulators have a 3/8" BSP-P male outlet & a 3/8" to 1/4" or 1/8" step down connector allows the hose to be fitted to the regulator.