S60r tcv hoses size?

[Markyb]

Thinking of replacing my vac hoses to the tcv, just wondered what internal diameter I should be looking at, ipd kit says they use 5mm, googling comes up with a range of 4mm to 6mm, just want to make sure that I get the correct size or does it not matter so long as it has a proper seal both ends?

[M-R-P]

4mm silicone and good clamps. Don't scrimp ;)