This is an E-flite 1S, 25C, 150mAh Li-Poly Battery Pack.

Features:
Covenient-use anywhere a powered USB port is available
DC Input: 5.0V 350mA
Works with a USB computer port, USB car charger adapter, or a USB AC power charger adapter
DC Output: 4.2V 300mA
Charges most 1S batteries using E-flite ultra micro connector
1 year limited Warranty

Includes:

(1) Battery

Specs:
Type: LiPo
Capacity: 150mAh
Voltage: 3.7V
Weight: 0.14 oz (4.15 g)
Configuration: 1S
Length: 1.47 in (37.5mm)
Width: 0.48 in (12.2mm)
Height: 0.22 in (5.5mm)
Maximum Continuous Discharge: 25C
Maximum Continuous Current: 3.75A
Connector Type: PH 1.5 (Ultra Micro)