Charge Markers simplify handling of batteries dramatically. Especially when you have many batteries, they are a helpful tool. The charge marker is glued to the battery with the applied adhesive strip, whereby a clearly visible place is best chosen. A slider indicates the charge status with red or green. After charging, set the slider to GREEN. After a flight or another discharge operation, set the slider back to RED.
Charge markers are manufactured in Europe and help reducing the risk of damaging your rc-model. Most pilots already had the experience with a discharged battery used again, or forgot which battery is discharged and which one full after a long day on the flying field. This inexpensive item makes things easier and measures only 27.5 x 9.2 x 2.75mm and 0.35g weight.