TheMatco Tools Automatic Transmission Refill Unit, No. ATFRK831, is designed for refilling automatic transmissions. This refill unit operates on shop air and features a pre-set pressure regulator to provide a constant flow rate. The unit's pressure relief valve ensures operator safety, and the cap clamp provides a second level of cap security when under pressure. Sealed transmission adapters provide coverage for most domestic and import vehicles. Made from lightweight composite materials.