I wouldn't solely rely on GPS Speed Scamera Detectors as mine has not always been aware of scameras which have been in place for a long time. The majority it will flag up, including Gatso, Truvelo, Specs and mine also had a laser detector and jammer. The Laser detector is all well and good in theory but by the time the detector has detected, the policeman has already obtained your speed, unless of course you have jammed it (the latter is not advisable as jamming is illegal)