{"product_id":"perimeter-technologies-four-pack-dog-fence-batteries-for-r21-r51","title":"Perimeter Technologies Four Pack Dog Fence Batteries for R21 R51","description":"\u003cp\u003eIn this review of the Perimeter Technologies Four Pack Dog Fence Batteries, the bottom line is simple: this is a budget-focused replacement designed for owners of Invisible Fence style receiver collars who want a lower-cost alternative with modern chemistry. The reviewer found these cells use a New and Improved Japanese lithium-ion construction that keeps collar weight down while offering higher energy density, making them a sensible option for pet owners who value longevity and savings over paying premium brand prices.\u003c\/p\u003e\u003ch2\u003eKey Features\u003c\/h2\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eCompatible replacement:\u003c\/strong\u003e Designed to replace the battery in R21, R22, R51 and Microlite receiver collars so you can get a direct swap without changing the collar.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eLithium-ion chemistry:\u003c\/strong\u003e Uses a high energy density Japanese cell that helps the collar run longer between charges while remaining lightweight for the dog to wear comfortably.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eDurable construction:\u003c\/strong\u003e Built with robust internal components that aim to extend service life compared with standard replacements.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWaterproof when sealed:\u003c\/strong\u003e The battery remains waterproof when the collar is reassembled using a tight rubber waterproofing seal, protecting the cell in typical outdoor conditions.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCost-effective pack:\u003c\/strong\u003e Sold as a four pack to lower the per-battery cost and reduce the frequency of shopping for replacements.\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch2\u003eWho It's For\u003c\/h2\u003e\u003cp\u003eThis product is best for owners of Invisible Fence style collars (R21, R22, R51 and Microlite) who prefer a lower-cost replacement and are comfortable installing a battery into their existing receiver. It suits people who prioritize value and a modern lithium-ion cell that can offer higher energy density and lighter weight compared with older chemistries.\u003c\/p\u003e\u003cp\u003eIt is not ideal for owners who require factory-approved parts for warranty or those who are unwilling to accept some variability in fit and performance based on customer reports. If a perfect OEM match or guaranteed compatibility is critical, purchasing an original equipment battery from the collar manufacturer may be a safer choice.\u003c\/p\u003e\u003ch2\u003ePros \u0026amp; Cons\u003c\/h2\u003e\u003cp\u003e\u003cstrong\u003ePros\u003c\/strong\u003e\u003c\/p\u003e\u003cul\u003e\n\u003cli\u003eLower cost per battery when bought as a four pack, offering clear value for money.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eLonger run time potential\u003c\/strong\u003e thanks to Japanese lithium-ion cells with higher energy density.\u003c\/li\u003e\n\u003cli\u003eLightweight design reduces additional burden on the dog compared with heavier cells.\u003c\/li\u003e\n\u003cli\u003eRemains waterproof when reinstalled with a tight rubber seal, protecting the collar electronics.\u003c\/li\u003e\n\u003c\/ul\u003e\u003cp\u003e\u003cstrong\u003eCons\u003c\/strong\u003e\u003c\/p\u003e\u003cul\u003e\n\u003cli\u003eFit and compatibility are mixed in customer reports, so some collars may not accept the replacement without modification.\u003c\/li\u003e\n\u003cli\u003eBattery life and performance vary by unit based on user feedback, so expectations should be tempered compared with factory originals.\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch2\u003eSpecifications\u003c\/h2\u003e\u003ctable\u003e\n\u003ctr\u003e\n\u003ctd\u003eBrand\u003c\/td\u003e\n\u003ctd\u003ePerimeter Technologies\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eIncluded quantity\u003c\/td\u003e\n\u003ctd\u003e4 batteries\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCompatible models\u003c\/td\u003e\n\u003ctd\u003eR21, R22, R51, Microlite receiver collars\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCell chemistry\u003c\/td\u003e\n\u003ctd\u003eJapanese lithium-ion\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eKey benefits\u003c\/td\u003e\n\u003ctd\u003eHigh energy density, lightweight, durable components\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eWater resistance\u003c\/td\u003e\n\u003ctd\u003eWaterproof when sealed with a tight rubber seal\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/table\u003e\u003ch2\u003eOur Verdict\u003c\/h2\u003e\u003cp\u003ePerimeter Technologies four pack batteries are a practical value option for owners who need a compatible replacement for R21, R22, R51 or Microlite collars and who accept some variability in fit and runtime. The improved Japanese lithium-ion cell and waterproof capability make them a sensible choice for everyday pet containment at a substantially lower cost than brand-name replacements.\u003c\/p\u003e\u003ch2\u003eFrequently Asked Questions\u003c\/h2\u003e\u003cp\u003e\u003cstrong\u003eWill these batteries fit my R51 collar?\u003c\/strong\u003e\u003cbr\u003eThey are designed to be compatible with R51, R21, R22 and Microlite models, but a small number of users report fit or acceptance issues so check the collar connection carefully during installation.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eAre these batteries waterproof?\u003c\/strong\u003e\u003cbr\u003eThe cells themselves are intended to remain waterproof when the collar is reassembled with a tight rubber waterproofing seal to protect the electronics.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow does battery life compare to the original?\u003c\/strong\u003e\u003cbr\u003eThe lithium-ion Japanese cell offers higher energy density and can provide longer run time in many cases, though customer experiences on longevity vary.\u003c\/p\u003e","brand":"Perimeter Technologies","offers":[{"title":"Default Title","offer_id":48612208869595,"sku":"B00BR0CA8M","price":35.6,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0724\/1043\/1707\/files\/61yUrVgEdLL._AC_SL1098.jpg?v=1778588168","url":"https:\/\/gearmusthave.com\/products\/perimeter-technologies-four-pack-dog-fence-batteries-for-r21-r51","provider":"GearMustHave","version":"1.0","type":"link"}