The department is clearing out the old field kit before the new sets arrive. On offer: twelve GPS handsets, eight soil augers, assorted tripods and about thirty metres of measuring tape. Everything works. The GPS handsets are eight years old and slower to fix a position than a phone, but they run for three days on two batteries, which a phone does not. Cash only, and please bring the right amount — we will not have change. Anything unsold goes to a partner school in Ghana, so do not feel you are rescuing it from a skip.