It's a classic query from the public! And a great opportunity to explain the differences - for those who are willing to listen to the information, of course. Chin chains - when the helmet is worn they should always be down, except for the band who wear them up on top of the helmet. Wrap them when the helmet is taken off, to keep them safe and stop then dangling. Infantry were issued 1 pair of trousers as a recruit, and then another pair once trained, so you would have 2 pairs at once and new ones issued annually. Which doesn't really help with cleaning, unless you have a lot of spare time 😂