4/3 A 3.7 Volt Lithium Ion 18500 Battery (1600 mAh) - Only Batteries
3.7V 600mAh LiPo Battery Kit for Arduino — Maker Portal
5mm Ultra Thin 95mAh Hot Selling Small LiPo Battery LP500829 3.7V | Polybattery.com
Li-ion battery 5000mAh 3.7V
Amazon.com: HXJNLDC DC 3.7V 2600mAh 903759 Rechargeable Lithium Polymer Replacement Battery for DIY 3.7-5V Electronic Product, Mobile Energy Storage Power Supply : Electronics
Lithium Ion Polymer Battery with Short Cable - 3.7V 350mAh : ID 4237 : $5.95 : Adafruit Industries, Unique & fun DIY electronics and kits