Suitable for iPod Nano 2nd generation 2G. Use the Apple iPod universal dock adaptor 3-Pack for iPod Nano (2G) to enable your iPod to fit the iPod universal dock and other products that use the universal dock system. Make sure to choose the dock adaptor that fits the iPod model you own. You simply insert the dock adaptor that fits your particular iPod model into the dock, then plug in your iPod. When you want to connect a different-size iPod, simply pop out the dock adaptor and insert a new one. Each package includes three dock adaptors. 3 batteries supplied.