The VoltWatch2 is On-Board Receiver Battery Monitor for 4.8V and 6V NiCd and NiMH receiver packs. LEDs provide instant, accurate battery voltage status of Low, Safe or Maximum voltage (Only one light at a time glows). Unit can be mounted on the side of the fuselage, or under the plane's canopy. Draws amazingly low current, from 4 - 34mAh, depending on the battery condition. Flip switch to select 4.8V or 6V battery. Dimensions/Weight: Length: 1 3/4" (45mm) Width: 5/8" (16mm) Height: 1/8" (3.2mm) Weight: 0.15 oz. (5g)