SlimeVR Full-Body Tracker

An affordable, comfortable, wireless, 360° solution for full-body tracking in virtual reality

Available for pre-order

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Oct 04, 2023

Project update 20 of 25

Certifications and Shipping Delays

by Eiren

In our previous update we mentioned that both Shipment 2 and Shipment 3 had arrived to Mouser. Sadly, some of it didn’t actually happen. Due to publication delays when we wrote the update, Shipment 3 wasn’t yet in Mouser’s warehouse, it was still waiting at US customs. We didn’t expect anything to go wrong there, so we proceeded to post the update.


If something can go wrong, it will, and it did. Shipment 3 was held by customs for more than a month, because they wanted FCC to review it. It took a very long time, and after which FCC concluded that SlimeVR lacks required certifications to be imported and sold in the USA.

This was a huge surprise for us, since we use certified Wi-Fi module ESP-12F by AiThinker, and it’s FCC ID is represented on the sticker on top of each Slime, and each box. What we missed was that it is only certified for use in mobile devices, not body-worn applications. In fact, it looks like a module can’t be certified for this, it’s each final product that has to be certified for a body-worn applications. We’re not a team of experienced specialists, and when we started the project, all our research showed that we didn’t need any additional FCC certifications for SlimeVR, so we decided to not go with a lengthy and expensive process of certification. In hindsight, this perspective was wrong, of course.

Here’s what we’re doing to fix it. We have reached out to multiple companies in Europe and in the USA, and will certify SlimeVR for body-worn application with FCC, and receive our own FCC ID. This shouldn’t be a problem, it just requires some time and money. We think we can finish with the process at the start of November.

After the certification is done, we would need to repack and reapply stickers to all the Slimes we already assembled and packed, including Slimes in shipments 3 and 4. We delayed Shipment 4 until customs released shipment 3, which turned out to be the right move, or it would have needed to go back to The Netherlands along with S3…

Current certifications sticker on all Slime trackers will need to be replaced

Since we can’t repack Slimes until we get new FCC ID, we can’t ship new Slimes to backers until then. If certification is done by the start of November, we expect S3, S4 and everything we’re assembling currently to be shipped to backers by the end of November. Shipment 4 includes all orders placed during the initial campaign (until October 12th 2021) and then some.

3.2 pallets of Shipment 4 already assembled and packed in The Cave waiting to be shipped to backers, but need to be re-packed now.


As with any tech product, manufacturing defects on any large scale are inevitable. At this moment, we shipped around 1500 sets of Slimes to backers, or over 8000 individual trackers, including extensions. Some of them, despite our best efforts at testing, had issues, mainly unresponsive sensor manifesting as a blue light on the sensor staying ON on boot (what we call "Blue Light Of Death"). We’re working on improving testing procedures and PCB design for the next revision and next batches to eliminate the issue, but either way, rest assured - SlimeVR is covered by manufacturer’s warranty! As is normal (and a law) in Europe, our warranty lasts 2 years since you receive the set and applies to all manufacturing defects. If you have any problems with your Slimes, please reach out to us via the contact form or email us, we’ll do our best to fix the issue or replace your device!

We also found out that the extension cables provided are prone to breaking. They’re also covered by warranty, so contact us if you need a new one. All new sets packed (including shipments 3 and 4) will get double the amount of extension cables - old and new ones, one of them is more comfortable, another more reliable. We’re also waiting for new cables from the manufacturer and as soon as we get them, all sets packed after will get an even better version.


We also should note that all parts shortages have been resolved for SlimeVR, we have supply of all parts for old and new orders, and we assemble new Slimes daily. We keep ordering new parts as we run out. The only bottle necks right now are assembly and certification. We also are still working on improving assembly speed by outsourcing some of it to local companies that specialize in assembly.

5 boxes of 4000 BNO085 each, 20000 total. We went from stressing out that we won't have enough IMUs to stressing out that we have too many parts on hand.

Other Stuff & Updates

This update took a while to post, and we’re sorry about that. The main reason is that the situation with the customs was ongoing, and it never felt like the right time to post an update here. If you want to know things as soon as they happen, join our Discord server where we post weekly updates with everything that’s going on + extra updates in case something important happens. We have a community over 33000 users that are passionate about Open Source and VR!

Speaking of the community, did you know that SlimeVR is fully open source? Everything we make is licensed under permissive licenses such as MIT and Apache 2, and all our software is built with the help of our contributors! If you want to support our contributors financially, check our our GitHub Sponsor page! All money collected goes directly to contributors (not including company owners, of course).

We’re once again thankful for your continued patience! This is a bump on our road, but not the biggest we had during more than two years of this project. We will get through it very soon, and hopefully next update will be about the shipping being resumed and many thousands of sets shipping to backers!

See you soon!

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