monoblock tail size

[LANCIABRAD]

Hi

I have just fitted a new basin with a monoblock tap, it came with two flexible tails, i fitted the small end to the tap fine but dont know what the other end connects to??

The ones on the tap i replaced went on to the end of a 15mm isolation valves but the end on the new one looks simular but smaller,

Any replies much appreciated

Many Thanks

 

[seco services]

had them many a times they come up about 12mm.
i just change them for a standard 15mm set and chuck the others.