Hybrid string cleaner and lubricant. It consists of a mixture of unique refined natural and premium mineral oil. String lubrication improves sound quality, reduces noises from fingers and allows faster and smoother gameplay. The applicator has an ergonomic shape and width of 6.3 cm, making it able to cover all the strings at once. It can be refilled with String Fuel Refill (sold separately). It contains no silicone ingredients, it has a delightful fragrance, is safe to use and also treats wooden fingerboards. Included is a microfiber cloth.