Lock Technology's LT991 Hollow End Line Taps help rethread female fittings without line removal in order to make it easier to service A/C and hydraulic line fitting threads that become corroded over time and otherwise break when disconnected. The hollow-end tap slides over flared end of line easily, rethreading the female connector. This eight-piece kit covers all popular sizes including 14mm, 16mm, 18mm, 20mm, 22mm, 24mm, 27mm and 1 1/8". Can be used on brake, oil, transmission and heater lines.