ACDelco Professional A/C Line O-Rings are used for forming a gas-tight connection between air conditioning components and are the high quality replacement ideal for many vehicles on the road today. A/C O-Rings should be lubricated with Viscosity 525 mineral oil to prevent leaks and fitting corrosion. These Professional, premium aftermarket replacement A/C line O-rings are manufactured to meet your expectations for fit, form, and function.