The Freeplay Sharpa/X-ray LED is based on the same design as the Sentinel and original Sharpa, but they replace the bulb with an Ultra-bright 7 LED cluster with a 100,000 hour rated life. The crystal clear casing of the XrayLED offers the user an exciting view of the process of converting human energy into light. The Sharpa LED has an opaque case. Thay have two brightness settings offering you a choice between efficiency (longer shine time) and maximum brightness. The efficient LEDs offer up to 20 hours of shine time on a full charge of 24 hours with the included AC Adapter, or 40 minutes of winding on the built-in generator. Just 30 seconds of winding can provide you with 20 minutes of light in the energy saving mode. A charge level indicator lets you know when you are winding at the best speed. The Sharpa/X-ray offers you the reliability of light anytime anywhere; no more dead batteries or burnt out bulbs!