Ebay offers Refurbished Anker 20W USB-C Portable Charger Power Bank for $13.99 (reg $39.99) with free shipping.

Product Description:
One of the slimmest Power Delivery portable chargers around. Combines PowerIQ and Power Delivery technology in an astonishingly portable package. About the same size as a mobile phone, you simply won’t find a more portable PD power bank. Anker’s MultiProtect provides surge protection, short circuit prevention, and many more advanced safety features to give you peace of mind. Works seamlessly with a wide range of USB-C phones, tablets, and more. The cool-blue LED displays remaining power and charging status. Designed to meet the tiny power requirements of smaller devices ensuring a fast and safe charge for every device, no matter the size.

• Portable Power PowerCore III Sense 10K is one of our slimmest PD power banks yet, with enough cell capacity to provide more than two charges for iPhone XS or Google Pixel, and almost one full charge for an 11"" iPad Pro.
• Triple Charging Modes 20W Power-Delivery USB-C port, PowerIQ-enabled USB-A port, and trickle-charging mode for low-power devices. Use the dual USB ports to charge two devices simultaneously. 
• Rapid RechargePower up your PowerCore in just 4.5 hours with a USB-C Power Delivery wall charger (not included).Recharging via USB-A charger and cable (not included) will take approximately 10.2 hours.
• Quality ThroughoutWith a sleek matte exterior and cool-blue LED light-wheel to display battery level, PowerCore Slim 10000 PD is premium both inside and out.
• What You Get:Anker PowerCore III Sense 10K Charger ,welcome guide, our worry-free and friendly customer service.