i agree with tony c . and if you dont have any metal near your pad it will clock the birds before they tread on the pad also all ets systems advertise they will clock through thick wooden boards some say six inches of oak so how far away will they clock . by the way the germans are developing a system for open door clocking they pass through a beam while flying to the box .. so it looks like we will have plenty of ets topics in the near future lolololol