-The pet collar is suitable for dogs with neck sizes of 8 pounds and more than 8 inches (small/medium/large/extra large dogs) multi-collar system, one of the transmitters can be paired with an unlimited number of receiver collars.-The collar receiver is waterproof and rainproof. When pets wander into the warning zone, the receiver will provide safe static correction vibration stimulation.How it works:1) Wall-mounted transmitter: The transmitter is the central controller of the entire electronic system. Make sure that the wire is set to loop.2) Receiver collar: If your dog tries to approach the wire boundary, the receiver (collar) will emit a warning buzzer first, and then continue to stimulate.3) How to install the system*Design your containment area and calculate the number of wires required.*Install the wall transmitter.* Arrange the peripheral wires.*Connect the peripheral wires to the transmitter on the wall.*Confirm that the transmitter is operating normally.*Set up the receiver, then test the closed system and adjust the field width.* Install boundary lines and training markers.* Install a collar for your dog and train your dog.Product packaging:1 *Indoor wall-mounted transmitter1 *Power plug1/2/3 *Adjustable receiver collar1 * 300m boundary line2 *Extra metal contacts20 *Training Banner1 *Test bulb2 * Screw1 *User Manual