Love the peace of mind of GPS tracking but want a collar that feels more like your pup? Duke & Fox brings personalized style to Fi with three ways to shop: a replacement collar for your existing device, a Fi Series 3+ bundle, or a compact Fi Mini added to your favorite collar.
The right choice starts with one question: do you already own a Fi device, or do you need one?
Compare Our Three Fi Options
| Option | What you receive | Who it’s for |
|---|---|---|
| Fi-compatible collar only | A Duke & Fox collar for your existing Fi Series 3 or 3+ device | Customers who already own a compatible tracker |
| Fi Series 3+ bundle | A Series 3+ device, a Duke & Fox collar, and a six-month Fi subscription | Customers who need the tracker and collar together |
| Fi Mini add-on | A separately purchased compact tracker added to a Duke & Fox collar | Customers who prefer an attachable tracker; excludes 1.5-inch-wide collars |
1. Fi-Compatible Collar Only: Refresh Your Existing Tracker’s Look
Already own a Fi Series 3 or Series 3+ device? Choose a compatible Duke & Fox collar and continue using the tracker you already have. Select your favorite pattern and the personalization options offered on the listing, then attach your compatible device.
This purchase includes the collar only. A tracker and new subscription are not included. A replacement collar changes your pup’s style; it doesn’t upgrade the device’s features.
Shop Fi-compatible collars — device not included
2. Fi Series 3+ Bundle: Device, Collar, and Six Months Included
Starting fresh with Fi? Our bundle includes a Fi Series 3+ device, one of our Duke & Fox collars, and a six-month Fi subscription.
Series 3+ offers live GPS tracking, safe zones, escape alerts, activity and sleep tracking, and behavior insights for barking, licking, scratching, eating, and drinking. It also features a built-in light and a waterproof device design.
Fi advertises battery life of up to three months. Actual charging frequency varies with use, signal conditions, and live tracking. See Fi’s current device information for details.
An active Fi plan is required for connected services. After the included six months, continued service requires an ongoing plan with Fi. Review activation and renewal terms when setting up your device.
3. Fi Mini: Add Tracking to Your Favorite Collar
Fi Mini is a compact tracker that attaches separately to a collar. You can purchase it and add it to any of our collars except 1.5-inch-wide styles.
Mini offers GPS/LTE-M location tracking, safe-zone escape alerts, location history, activity and sleep tracking, and behavior monitoring. Its lightweight design makes it an option for customers who prefer an attachable device.
Fi lists IP68 waterproofing and battery life of up to two months, depending on use and conditions. An active Fi plan is required for connected services; check your selected listing for included membership details.
Choose a collar and add Fi Mini
Duke & Fox Fi Collar Size Guide
Our Fi collar sizing differs from our standard collar sizing and may differ from Fi’s own sizing. Measure your dog’s neck where the collar sits, rather than measuring the total length of their current collar. Don’t add extra inches or size up unnecessarily.
| Size | Neck circumference | Width |
|---|---|---|
| S | 13–15 inches | 1 inch |
| M | 16–18 inches | 1 inch |
| L | 19–21 inches | 1 inch |
| XL | 22–25 inches | 1 inch |
Important for size small: the adjustment will likely cover some embroidery. Choose an engraved buckle if you want to avoid having embroidered details covered.
Custom sizing is available. Email help@dukeandfox.com with your dog’s exact neck measurement if they fall between sizes or you need guidance.
For a standard collar with Fi Mini added, follow that collar’s own size chart instead of the Fi Series 3/3+ chart above. Choose a width other than 1.5 inches.
Visit our Fi sizing page or step-by-step measuring guide. After delivery, check that two fingers fit comfortably beneath the adjusted collar and that it stays secure.
Personalized Style With Helpful Identification
Choose the embroidery, engraved buckle, or combined personalization offered on your listing. A name and current phone number give someone who finds your dog a way to contact you directly. Check engraved information regularly as hardware wears.
Before You Order
Collar-only purchases don’t provide GPS tracking on their own. You need the compatible tracker and appropriate active Fi service. Series 3 devices don’t gain Series 3+ behavior features by switching collars.
A waterproof tracker doesn’t make every collar suitable for swimming. The device and collar material have separate care needs. Our fabric collars aren’t recommended for frequent swimming or rugged wear.
Connected tracking depends on device charge, location conditions, and supported network coverage. Keep your dog’s microchip and visible contact details current alongside GPS tracking.
Find Your Pup’s Fi Match
Already own a Series 3 or 3+? Choose a compatible collar only. Need both the tracker and collar? Choose our Series 3+ bundle. Prefer a compact attachable option? Add Fi Mini to an eligible collar.
Still deciding? Email help@dukeandfox.com with your dog’s neck measurement, tracker model if you have one, and the collar you love. We’re happy to help!https://cdn.shopify.com/videos/c/o/v/2199615f96894e30886265f560ff0d29.mp4
