Adafruit Industries Lithium Ion Battery - 3.7v 2000mAh - Micro Center
Adafruit Battery Packs Lithium Ion Battery 3.7v 2000mAh – kjdElectronics
Adafruit Industries - 328 - Lithium Ion Polymer Battery,Rechargeable,3.7 V,2.5 Ah,2x2.55x0.3"(51x65x8mm) - Allied Electronics & Automation, part of RS Group