37 INSTALLATION, SERVICING, MAINTENANCE, AND REPAIR OF REMOTE TRAINING SYSTEMS COMPRISING ELECTRICAL RADIO FREQUENCY TRANSMITTERS AND REMOTELY CONTROLLED RECEIVER COLLARS; BARKING CONTROL COLLARS; ELECTRONIC PET CONTAINMENT SYSTEMS COMPRISING ELECTRICAL TRANSMITTERS AND ELECTRICAL RECEIVER COLLARS; ELECTRICALLYCONTROLLED PET DOORS AND ELECTRICAL ANIMAL TRACKING AND LOCATING SYSTEMS COMPRISING ELECTRICAL RECEIVERS AND ELECTRICAL TRANSMITTER COLLARS