This is the Shearwater NERD 2 Charging Clip Features: Can provide 5 full charges to the NERD 2 Connects to any USB cable Splash proof USB cable can connect to any USB port or the power bank supplied by Shearwater USB cable can connect to any USB port or the power bank supplied by Shearwater The Charging clip attaches to the back of the NERD where the two brass contacts are located. All you do is press (snap) into place when you want to charge the unit. When connected to a USB charging port will then charge the internal battery in the NERD. Without that clip, you cannot charge the NERD. The NERD will fully charge from zero in about an hour and the internal NERD battery is then good for about 18 dive hours.