The YDL 3.7V Rechargeable Lithium Polymer Battery Pack with PH2.0mm JST Connector is a high-performance, ultra-thin, and lightweight power solution designed for a variety of devices, offering huge capacity and over 500 charge-discharge cycles while retaining 80% of its original power, thanks to advanced lithium polymer technology with low self-discharge. Featuring a JST PH2.0mm connector (red wire for "+", black wire for "-"), this battery is perfect for MP3/MP4 players, Bluetooth headsets, GPS trackers, smartwatches, dashcams, ring video doorbells, pet trackers, and more, delivering excellent safety with built-in anti-short circuit and over-current protection that meets international standards. Before use, check voltage and polarity to avoid damage—incorrect connections or high-voltage charging can harm the battery or device, and if the plug doesn’t match, you can cut and rewire it, noting the 1-3mm size tolerance. This reliable, explosion-proof, and durable battery is the ideal choice for anyone needing portable, long-lasting energy for electronics or DIY projects.