The CW-20 is an all-purpose high performance security metal detector at an economical price. It is capable of locating all types of metal while offering the user a choice of three frequencies to eliminate the possibility of any interference. The CW-20 also contains a “momentary low” switch to eliminate interference from steel rebar built into many concrete floors. It runs on one 9 volt battery and can be set to either quietly vibrate when finding metal or emit a high pitch sound. Backed by Fisher’s two year product warranty.