This accessory connector for Victron's Blue Smart IP65 chargers features LED indicators to show the state of charge of the battery to which it is connected.  These provide a quick and easy visual indication of the 'health' of the battery without needing to reach for your multimeter.
LED indication

Green - battery 100% charged
Amber - battery 60-80% charged
Red - battery < 60% charged
No LED - immediate re-charge required

M8 eyelets allow for easy and secure connection to the battery and a splash-proof fuse holder fitted with 30A standard blade (ATO) fuse protects against accidental shorts. This connector is useful if you have a hard-to-reach battery as you can leave the eyelets permanently connected to the battery and just plug the charger into the connector when required.