I have a rolled leather one at 5mm. I had ordered the 6mm but the lady advised me to go for a 5mm (she knew more than me) and its fine. I can't compare as I've no idea what the others look like, but mine is ok (in the puppy photo forum I have a post called ' new fur-do' and you can half see the lead on there to see the size. Can't send the link as I'm on my phone and I have no idea how I do it lol.