SureCall 5-Band RF Signal Detector [700-2100mhz]
[SC-METER-01]

It is a good product, sturdily built, easy to read once you understand how to use it. It would be better with better documentation and internal storage. It was difficult to figure out how to tell which frequencies were in use by each carrier (you can find that info from the FCC, and it varies based on the test location). It would also be nice if it had an internal storage and a low-cost GPS receiver that would allow you to store readings for a given location. Otherwise you just have to take notes yourself. Finally, be aware - this works in the US only - it does not cover all of the Canadian cellular frequencies.