This is the Futaba BR-3000 Battery Checker.

FEATURES: Checks the state of the following battery packs;
2-7 cell LiFe, LiPo and Li-Ion packs with JST-XH connectors
4-7 cell NiCd and NiMH packs
Battery pack total voltage display and remaining capacity are
displayed on a bar graph and in percent
Voltage of each cell of a lithium battery pack can also be displayed
Operates on the power supplied from the connected battery
One year limited warranty through Hobby Services beginning at date of
purchase

INCLUDES: Futaba BR-3000 Battery Checker

SPECS: Voltage display error: ±1.5%
Dimensions: 3.3 x 2.5 x 0.6" (85 x 63 x 15mm) excluding projecting
parts
Weight: 1.8oz (52.6g)
Display range;
Total voltage: (Ni type) 4.0~17V, (Li type) 5~34V
Cell voltage: (Li type) 1.1~4.9V
Operating temperature: -10~+45°C
Storage temperature: -20~+60°C

COMMENTS: The BR-3000 Battery Checker can only be used with the battery packs
listed above. It cannot handle batteries of other cell sizes and
types. The checker display is based on voltage. Since the voltage
changes with the individual battery and the ambient temperature,
use the remaining capacity display as a criteria only.