These lost their colour after 2-3 months and turned a strange brassy colour. They have since welded themselves to the valves of my tyres. Fortunately I managed to use a hacksaw to remove them, although this took a couple of hours, and I don't think I have done any damage to the tyres but only time will tell. I should have realised that you only get what you pay for and you can't really expect much at this price. Beware.