If you are thinking of buying your first gps system take a look at clive thomas pathfinder gps for walkers guide first as it will provide you with everything you need to know before you part with your pounds he writes in a very clear style without using jargon to make understanding gps simple in the book youll find expert tips reliable advice valuable information and practical guidance to help you on your way using an entry level garmin etrex gps system clive details how a gps functions