I had one similar to that 20 or 30 years ago. It was sold as a solar cigerette lighter novelty lighter. Yoe they do work. No they are not worth the weight and bulk. It is basicly a toy. You would be better off getting a credit card sized fesnel lens. A lot smaller. Weighs next to nothing. Can fit in your wallet. Magnifies small objects. And will start a fire quicker under the same conditions. But the biggest factor is the lens costs less than a buck. The last time I looked the price was $.49 for one versus almost $ 12.00.