---
product_id: 31606883
title: "Perimeter Technologies Invisible Fence R21 Replacement Collar 7K - 1 Dog and Free Backup Collar Strap"
brand: "extreme dog fence"
price: "$345.75"
currency: USD
in_stock: true
reviews_count: 8
url: https://www.desertcart.us/products/31606883-perimeter-technologies-invisible-fence-r21-replacement-collar-7k-1-dog
store_origin: US
region: United States of America
---

# Invisible Fence Compatible Frequency Selection 7K American Manufactured Perimeter Technologies Invisible Fence R21 Replacement Collar 7K - 1 Dog and Free Backup Collar Strap

**Brand:** extreme dog fence
**Price:** $345.75
**Availability:** ✅ In Stock

## Summary

> 🐶 Keep Your Pup Safe in Style!

## Quick Answers

- **What is this?** Perimeter Technologies Invisible Fence R21 Replacement Collar 7K - 1 Dog and Free Backup Collar Strap by extreme dog fence
- **How much does it cost?** $345.75 with free shipping
- **Is it available?** Yes, in stock and ready to ship
- **Where can I buy it?** [www.desertcart.us](https://www.desertcart.us/products/31606883-perimeter-technologies-invisible-fence-r21-replacement-collar-7k-1-dog)

## Best For

- extreme dog fence enthusiasts

## Why This Product

- Trusted extreme dog fence brand quality
- Free international shipping included
- Worldwide delivery with tracking
- 15-day hassle-free returns

## Key Features

- • **Bonus Backup:** Includes a free eXtreme Dog Fence backup collar strap.
- • **Optimal Frequency:** Default 7K frequency minimizes interference.
- • **Quality You Can Trust:** Proudly made in the USA with imported parts.
- • **Tailored for Your Pup:** Designed for one dog, ensuring a perfect fit.
- • **Seamless Compatibility:** Works with Invisible Fence systems prior to 800 Series.

## Overview

The Perimeter Technologies Invisible Fence R21 Replacement Collar is designed for compatibility with Invisible Fence Brand inground systems prior to the 800 Series. It operates on a default 7K frequency to minimize interference and is proudly manufactured in the USA. Each order includes a free backup collar strap, ensuring your pet's safety and comfort.

## Description

Perimeter Technologies Invisible Fence R21 Replacement Collar 7K - 1 Dog and Free Backup Collar Strap

## Features

- INVISIBLE FENCE COMPATIBLE - This Collar Will Work with Invisible Fence Brand Inground Fences Prior to the 800 Series, Including ICT-700, ICT-725, ICT-750, ICT-775, ICT-150, ICT-250, ICT-100, ICT-75, ICT-50, AT-950 Indoor Transmitter, CT-4000
- NOT COMPATIBLE - These Collars Will NOT Work with Invisible Fence 800 Series Systems or Later Fence (Including the Titanium Series). . Will NOT work with Boundaries Plus Fence. Nor Will They Work With the Shields Indoor Avoidance Transmitters
- FREQUENCY SELECTION - Most Invisible Fence Brand Underground Fence Systems Run on 7K, by Default. Systems that were Setup with Neighboring Fence Systems in Place May Run on 10K, to Avoid Interference
- AMERICAN MANUFACTURED - This Collar is Manufactured U.S.A. With Imported Parts
- Each Pet Fence Collar Order Comes with a Free eXtreme Dog Fence Backup Collar Strap

## Images

![Perimeter Technologies Invisible Fence R21 Replacement Collar 7K - 1 Dog and Free Backup Collar Strap - Image 1](https://m.media-amazon.com/images/I/41EUzc4etPL.jpg)
![Perimeter Technologies Invisible Fence R21 Replacement Collar 7K - 1 Dog and Free Backup Collar Strap - Image 2](https://m.media-amazon.com/images/I/51WGIfcUQUL.jpg)
![Perimeter Technologies Invisible Fence R21 Replacement Collar 7K - 1 Dog and Free Backup Collar Strap - Image 3](https://m.media-amazon.com/images/I/5181apgViaL.jpg)
![Perimeter Technologies Invisible Fence R21 Replacement Collar 7K - 1 Dog and Free Backup Collar Strap - Image 4](https://m.media-amazon.com/images/I/61WkO-EiHZL.jpg)

## Available Options

This product comes in different **Size** options.

## Customer Reviews

### ⭐⭐⭐⭐⭐ 5.0 out of 5 stars







  
  
    amazing customer support from company
  

*by M***S on Reviewed in the United States 🇺🇸 on July 16, 2022*

I just want to say thanks for the customer support that I received this week. I am blown away by how helpful the associate was to me. I wish I remembered her name, but I don't. I was a bit stressed when we talked.One of my dog collars had become damaged and quit working. My large Lab mix and medium hound mix are very rowdy when they play, and the gray part had a crack in it and it no longer worked. Any other time I could have contained them indefinitely in the safety of the barn yard which is fenced with chain link. But we were about to leave town and the friends who were coming to feed them would need to open the barn to put in food and water. They are good dogs but very dependent on that little beep to turn them around when they are going toward the back of the property.When friends open the barn the dogs always explode with joy into the property surrounded by the underground fence where they like to run during the day. Naturally when I discovered the broken collar I ordered a replacement. The fastest option was Amazon Prime, but when it came it didn't work. I was so worried; I honestly don't think I could bear to kennel my dogs.I called Perimeter, but the got no answer, messaged, then just collapsed on the couch to consider options. But the phone rang and it was Perimeter calling back. She was so patient as I walked around my house trying to pair the collar, she even had to call again when the signal dropped. It turned out that I had purchased a collar of the wrong series. She said I could order one from her but I explained my short time constraint. She gave me an express shipping option and even took the collar herself to the UPS store so that I would get it in time, which I did.I can't begin to say what this meant to me. I have never been so grateful for a business interaction. The associate was calm, patient, kind, and just solved my crisis as if it was easy. She listened and understood the situation and handled it completely. I just want to say thanks again even though that doesn't begin to express it.

### ⭐⭐⭐ 3.0 out of 5 stars







  
  
    Some work some don’t
  

*by A***N on Reviewed in the United States 🇺🇸 on June 26, 2023*

I ordered 3 collars. 2 work I can’t get the third to work. Tried to different properties with several batteries. Didn’t work. The other two are goochie.

### ⭐⭐⭐⭐ 4.0 out of 5 stars







  
  
    Almost perfect
  

*by M***K on Reviewed in the United States 🇺🇸 on February 4, 2023*

So far I have purchased three of these items at different times.  As other reviews have mentioned, one of my older ones did develop a crack in the casing.  All are functioning well and it’s an overall good alternative to buying OE invisible fence collars.

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*Product available on Desertcart United States of America*
*Store origin: US*
*Last updated: 2026-02-11*