I have seen in the iFAB book that it advises you to get a special coin for it. And then on various refereeing sites like 'The referee store' you can buy a coin for like £7. What do you people use? Personally I just use whatever coin I have in my bad whether that be 2p, 10p, 50p, £1 or £2. However that has led to me sadly losing several pound coins on the pitch.