No big secret the 550 meter is very inexpensive compared to the 180.Most hunter use a meter to cherry pick for silver coins and nickles for hunters use to the 180 meter.Very simple solution adjust the 550 meter to 480.Much easier to watch 479-480 for silver and copper ,468-470 for Zinc ,460-470Early Wheat's and IHs ,377 Jefferson ,373-381 Buffalo and V nickles.Later Ron