Direct Info from Product Website : https://www.co2art.eu/products/manifold-block-for-pro-elite-series-regulator

If you need to inject CO2 into more than one diffuser or aquarium this manifold comes with everything you need ;

Included Bubble counter with integrated check valve
Built-in high precision needle valve
Tools to install block into your existing manifold
With very easy installation your additional diffuser will be up and running with no time.

ONLY WORKS WITH PRO-ELITE MODEL