If it's the Nite-ize I'm thinking of, it will only fit the AA models. IIRC the AAA model has a thinner head as well as the body.
Multi adaptor for a wide range of lights. Its brighter than the Nite-ize but I don't know about the run time.

There is an LED mod for the Solitaire. Its a serious upgrade in light output both in color and amount. The only problem is that the head doesn't thighten down like it will with the original bulb. The front o-ring doesn't completely seal.