The design,
in the open.
Sun on top, sky at the crown.
In the V1 design, everything electronic lives in one sealed top unit on the neck. The GNSS antenna sits at the crown with nothing over it, and two solar panels on the sloped faces either side keep the battery topped up without shading it.
Gaskets and screws, not potting, so the battery, board, and panels can each be replaced.
The weight at the bottom does work.
A collar needs mass under the neck to keep the antenna facing up. Instead of a dead counterweight, the bottom is a bay. Every collar ships with ballast.
Swap in a Battery Extension for long winters and heavy shade, or a camera module with a GoPro for footage and research. Each module sits in the same cradle and weighs the same, so the collar balances whichever one is fitted.
The fence runs on the collar. The boundary lives on the collar and is checked there, so the fence keeps working with no signal. The cellular link is for reports and new boundaries, never for containment.
Any software can run it. The collar will speak an open, documented device protocol, with open-source code to speak it back. openpasture's software is one option; your own scripts, another farm app, or a research pipeline work the same way. Building or buying a collar never obliges you to use ours.
Design targets.
What V1 is being designed to meet. None of these has been measured on an animal.
The one measurement so far: the first prototype's fix settled to 2.2 m under open sky on .
| Position error, open pasture | ≤ 2.5 m, CEP50 |
|---|---|
| Position error, under canopy | ≤ 4 m |
| Fix when requested | ≥ 99 % |
| Runs with no sun | ≥ 60 days |
| Charging by the farmer | none for a season |
| Total weight | ≤ 1.2 kg |
| Setup per collar | < 2 minutes |
| GNSS | u-blox M10, four constellations |
| Cellular | LTE-M, NB-IoT fallback |
| Battery | 2 × 26650 LiFePO4, about 22 Wh |
| Solar | 2 ETFE panels, about 1.5 W |
| Bay modules | 450–650 g each |
| Strap | standard 50 mm cattle neck strap |
| Sealing | IP67 target, vented |
| Cue | sound first |
Assembled
from$2491
Built, tested, and sold by openpasture, ready to strap on. A $50 reservation per collar holds your place; you configure and confirm your order once the V1 design is final. First batch to early adopters in Q1 2027.
- Top unit, strap, and ballast module
- Battery Extension and camera module as add-ons
- Fully refundable until you confirm
Build it yourself
~$260in parts
The same collar from breakout boards, a bought strap, and printed parts, at retail on today's list. Plus the nRF9151 development board, shipping, and test gear.
- Every part, vendor, and price
- What to print it in
- A battery setup with nothing to configure
Where it stands
- Prototype 01
- first GPS fix
- Firmware
- boots, loads a boundary
- Collar protocol
- drafted
- Field test
- not started
- Parts list
- published
One collar first: walk tests, then on sheep, alongside a farm's existing fence. Sound first; an electric pulse only once there's the welfare logic and field data to do it responsibly.
Built hardware before?
1$249 is a back-of-the-envelope target for the assembled OpenCollar (top unit, strap, and ballast module) in US dollars, not a quote. Reaching it likely depends on designing our own custom board, which we plan to sell on its own as well, alongside the other components and the 3D-printed designs. It is our target, and we may not hit it. It excludes add-ons, shipping, taxes, and fees, and the actual price is confirmed before you order.
2The OpenCollar is a prototype. Specifications are V1 design targets, not measurements, unless marked as measured. Our targets are the prototype complete by mid-October 2026, the V1 design final by the end of 2026, and the first batch delivered to early adopters in Q1 2027. They are targets, not commitments, and may change.
3The reservation fee is $50 per collar, paid through Stripe. It is fully refundable at any time before you confirm an order, and applied to the purchase price when you do. A reservation is not an order and does not guarantee a price or a delivery date. See the terms.
4openpasture software features such as proposed and scheduled moves describe the design in progress. What works today is in the release notes and on the build log.