And one more question (thanks for your patience!). Does Coiltek have a different series of serial numbers on their Digger coils with an additional zero in the beginning? The Coiltek site indicates the "submersible" Digger coil serial numbers start at "0301" but I see that my serial number starts with two zeroes, as on "00xxx". I thought perhaps the expanded range is because they sold so many of them that 9999 units didn't give them enough room!