This is a 3-cell battery holder designed to hold three 18650 lithium-ion batteries. It's typically made of black plastic and features spring contacts to securely hold the cylindrical batteries in place and establish an electrical connection. Here's a breakdown of its features and uses: Description: * Number of Cells: Holds 3 x 18650 batteries. * Material: Usually made from durable ABS plastic, which is often flame-retardant and high-temperature resistant. * Contacts: Features metal spring contacts (often nickel-plated with copper) to ensure good electrical conductivity and a secure fit for the batteries. * Wiring: Comes with pre-attached red and black wires for positive and negative connections, making it easy to integrate into circuits. The wires are typically thin and designed for low to moderate current applications. * Mounting: Often has mounting holes or features that allow it to be screwed or otherwise fastened to a surface or within an enclosure. * Polarity Markings: Usually has clear "+" and "-" markings inside each cell compartment to ensure correct battery insertion. * Size: The dimensions will vary slightly between manufacturers, but it's designed to snugly fit standard 18650 batteries (approximately 18mm in diameter and 65mm in length). Uses: This type of 18650 battery holder is commonly used in various DIY electronics projects, portable devices, and applications where a reliable and easily replaceable power source is needed. Some common uses include: * DI