I wanted something for hunting purposes, so I bought OTTO's for the "natural sound" feature.
My first set of OTTO NoizeBarrier Micro's (purchased in Nov 2020) crapped out after one month of daily use when they stopped holding a charge for more than 4-5 hrs. (They claim up to 16 hrs of continuous use in the specs). OTTO replaced them promptly and the replacement set made it through the remaining 2020 season and all of the 2021 season without any drama. The 2022 hunting season was also uneventful, so I figured that first set was a "lemon".
When I brought them out for the 2023 season in November, again I immediately experienced a failure to hold a charge for more than 4-5 hrs. I returned them to OTTO in late November 2023 for repair and/or replacement, but I haven't heard back from them as of today.
When they work, they're the bomb for hunting purposes, but I suspect this technology might not be ready for prime time. If this latest set isn't replaced under warranty, this will turn out to be an costly experiment that I will not repeat.