A/C Pro AC-008 Professional Formula Ultra Synthetic Car Refill helps make recharging your car's A/C easy and accessible. This auto A/C recharge features an additive formula that seals leaks in rubber hoses, gaskets, and O-rings, and protects your A/C system while providing 2x cooling boosters, versus the next leading brand of A/C recharge kits. Each helps eliminate acid and moisture buildup to protect and extend the A/C system's life. To use, find the low-pressure port, turn on the car and AC, read the pressure, and charge the system.