The standard VX PIR is produced by the world leaders in PIR technology, a company called Optex. We use these PIR's as they are the best in the world and we modify them for GSM communication.
The VX402 GSM PIR is a dual beam PIR. Dual beam means that both beams must be interrupted in order to produce an activation. Essentially these PIR's when installed according to instructions, will not detect anything smaller than 1 meter tall, I.E. Dogs, cats, foxes, birds etc.
