Potter EVD-2C Safe/Vault PakThe EVD 2, Electronic Vibration Detector System, is listed by Underwriters Laboratories, Inc. for primary protection of Mercantile or Bank, safe or vault, ATM machines and supplementary protection of interior units such as file cabinets, display cases, walls and ceilings. The System must be used with an appropriate UL listed control unit. Main Features Detects all common threats to safes and vaults Reliable, sensitive piezo sensor technology