Do not be caught out, most people/plumbers automatically assume that the tap will be supplied with 1/2" flexible tails. By the time they have found out that it is 3/8" it is usually too late! Be prepared.

15mm spigot fits directly into a standard 15mm isolating valve (NOT INCLUDED) allowing you to screw your 3/8" tap tails on the threaded end

You will receive 2x brass compression INSERTS ONLY (SEE SECOND IMAGE). The flexis, isolating valves and copper pipes in the pictures are purely for descriptional purposes.

If you are struggling to find what you need, look at the images comparing the end of the flexible tails to a 5 pence piece. If you have a standard 1/2" female fitting, the 5p will sit in the end nicely. If however you have a non standard 3/8" female fitting, the 5p will not go in at all.