In the past we have recommended Trust Fire Li-Ion 26650 batteries, which were slightly longer and had protection circuits built in. These adapters are designed for our current 26650 Li-FePO4 batteries or 26650 High Capacity Li-NiMnCo batteries to work in older (v2.7 and earlier) battery tubes, as the dimensions of the batteries the tubes are designed for has changed.
All OpenROVs purchased through this website should have contained these parts. You only need to buy this IF you are planning to use the Li-FePO4 batteries AND you have a version v2.5, v2.6, or v2.7 with a serial number below 1200. All v2.7 kits came with these adapters.
Have questions for us? Please reach out to our support team.