For $30 it's the DOX for your Echo Dot
From Ninety7, DOX is a portable battery for the 2nd Generation Amazon Echo Dot , designed to provide rechargeable, cord-free mobility at home or on-the-go. With up to up to 10 hours of cordless use, you can unplug and take Alexa anywhere you choose without the hassle of cables and outlets.
4 LED lights integrate seamlessly on the front of DOX, indicating how much battery life remains before needing a charge. Dimensions Height 63mm / 2.5" Diameter 93mm / 3.7" Weight .8 lb 12.8 ounces Compatibility Amazon Dot Echo (2nd Generation)
Priced right at $29.95