JUST BECAUSE YOUR RECEIVER MAY LOOK LIKE THIS ONE IT DOES NOT MEAN IT WILL BE COMPATIBLE WITH YOUR SYSTEM.  IF YOU HAVE ANY QUESTIONS ABOUT THE COMPATIBILITY OF YOUR TRANSMITTER WITH THIS 700 SERIES, 10K RECEIVER, PLEASE ASK.   I AM HAPPY TO HELP!

Invisible Fence R21 V2.0 RECEIVER 700 Series 10k Frequency Receiver With A New Perimeter Brand Battery And Used Collar.  Item's pictured are the exact one's you will receive.  Will ship USPS Ground Advantage Mail. 

IMPORTANT, PLEASE READ:
This collar is compatible with the following Invisible Fence Transmitters:
ICT-50/50A
ICT-100/100A
ICT-150
ICT-250
ICT-700
ICT-725
ICT-750
ICT-775
IFA-12 Indoor Barrier
Invisible Gate
The transmitter must be set to 10k frequency for the receiver to function.  To check your frequency, remove the lid from your transmitter and look for a small black switch which will offer a choice of 7k or 10k.  Set it to 10k.  The ICT-50 and ICT-100 may just have a sticker on the transmitter board telling you what frequency it is set to.  This 700 Series receiver is NOT compatible with 801, 802 (unless they have a 7xx option on their circuit board) and Boundary Plus transmitters.  IF YOU HAVE ANY QUESTIONS ABOUT THE COMPATIBILITY OF YOUR TRANSMITTER, PLEASE ASK.