These are supplied with the Brupak and stainless boilers. With other makes you'll need to buy one!
One is universal and fits most 5 gall/40 pint boilers eg, The Ritchie, Brupak and Electrim. It has the push fitting.
The other fits the big stainless boilers only-If your boiler is plastic or enamel it's the other one.
You could make your own easily enough but this does save the time!