YOKME&reg; Digital Wireless LCD dog Training Shock collar with 100LV of Shock and Vibration, Remote Control Provides a professional 100 level shock and 100 level Vibration with Rechargeable LCD digital remote control electric training Collar LCD digital remote control electric training collar remote control electric shock devices Convenience of easy-to-read LCD screen shows the stimulation level. Over 3,000 different identity codes to prevent conflicts with other e-collars. The system can be used for 1 or 2 receivers.(the additional receiver must be the same type as your previous one and purchased from us) Note: Saving beads switch inside will ring if you shake the receiver. Every time you pull out the batteries, you need to match code again.