Working with the vendor

If a school is required to go out on bid for one or more hand-held metal detectors, it is recommended that the contract require the following optimal features:

• A variable pitch of alarms that provides more information to the operator using it, i.e., a softer squeal for an innocuous item, like a zipper, and a louder squeal for a bigger, more suspicious item.
  
• A detector paddle or zone that is at least 10 inches long.
  
• A signal that indicates the battery is beginning to run low, as opposed to an abrupt termination of operation.