Fasfil butane is a highly pure fuel known for its 5X (quintuple) refinement process, which removes impurities to prevent clogs and corrosion in lighters and torches. It's marketed as a premium, high-quality fuel designed for refillable devices like cigar torch lighters, culinary torches, and portable stoves. The product typically comes in a 10.15 oz (or similar) canister with a multi-sized adapter cap for universal compatibility with various lighter valves.