This little battery sleeve fits the small 3.7v 150mAh Lithium Ion Polymer Battery available from Adafruit Industries (Product ID: 1317). It currently has a pair of sewing tabs. It was designed for wearable tech fashion projects to protect your LiPo battery from harm. From Chapter 8: Programmable Sewn Circuit Cuff from our book [Make It, Wear It: Wearable Electronics for Makers, Crafters, and Cosplayers](https://www.ampedatelier.com/make-it-wear-it). If you make one and post on social meda tag it with **#makeitwearitbook** so we can see it!