Amazon.com: HXJNLDC DC 3.7V 5000mAh 955565 li-ion Lithium Ion Polymer Battery Replacement for DIY 3.7-5V Electronic Product, Mobile Energy Storage Power Supply : Electronics
Lithium Polymer Akku - 3.7V 4000mAh - 90 x 60 x 6mm | Akku-King der Akkuprofi: schnelle & sichere Lieferung!
AKKU 22707: Li-ion battery, 21700, 3.7 V, 4000 mAh, includes MicroUSB chargi at reichelt elektronik
UltraFire BRC 18650 4000mAh battery 3.7V with PCB and button top