These valves replace the existing tails, they are the same, I have no idea what you are thinking about, this is a simple mod to your existing radiator! View attachment 426817
this is one of mine
and an unmodded valveView attachment 426827
Putting these valves in both ends allows you to isolate the water in the radiator, if you can’t see how this works, perhaps you should consult a plumber!
Where are you ?
Those pipes look as if they're solvent weld..... never seen that in the UK