An easy way to keep track of which batteries are charged and which ones are depleted; as well as protecting your batteries from unintentional shorts. Just pop the red cap on the battery after flying and and the green cap after charging.
3D printed in TPU (Thermo plastic polyurethane), these XT60 caps are soft and pliable making them easy to install and remove. They are also marked "Empty" on the red ones and "Full" on the green ones.
Sold in packs of 12. 6 red and 6 green.