The colours show you the battery charge! Panasonic BQ-CC55 charger for AA and AAA batteries.

Panasonic advanced Ni-MH battery charger has a timer and auto shut off feature.
Rechargeable battery charger has 4 LED lights to show battery life, charge progress and percentage, and charging status.
Advanced Panasonic chargers have Auto shut off feature, detect voltage and stop charging just after overflow.
Panasonic advanced chargers can be used for both AA and AAA type eneloop and eneloop pro batteries.
Advanced eneloop battery chargers can charge up to 4 batteries individually.
eneloop advanced charger comes with a retractable AC plug.
This advanced charger takes approx 1.5 hours to charge 1PC/2PCS and 3 hours to charge 3PCS/4PCS of both AA and AAA eneloop batteries.