This is the VoltWatch2 on-board Receiver Battery Monitor for 4.8V and 6V NiCd and NiMH receiver packs. 

This mounts on the outside, so you can see at a glance the status of the receiver battery mounted inside.

If you are little more creative, you can cut out a small window into top of your battery box and glue on small plastic/perspex window for visual display.

FEATURES: 7-LEDs provide instant, accurate battery voltage status of Low, Safe,
or Max. Only one LED glows at a time
Small switch to select 4.8V or 6V battery
Very lightweight, only .15oz (4.3g)
Draws amazingly low current - from 4-34mA depending on the battery
voltage
Plugs into any open receiver channel using a Futaba J connector


INCLUDES: One VoltWatch2 On-Board Receiver Battery Monitor w/Futaba J plug
One 1.5"x1" piece of double sided mounting tape


SPECS:    Length: 1.65" (42mm)
Width:   .63" (16mm)
Height:  .16"  (4mm)
Weight: .15oz (4.3 grams)
Current Draw: approx 4-34mA
Lead Length: 198mm (7.79")