This is a cap with an O-ring for installation on the air conditioning valve of a standard passenger vehicle. ・Missing when purchasing a used car ・Missing after a regular inspection ・Cracked due to aging This is for when replacement or installation is needed. This is a set of 2, with 3 high-pressure side caps and 3 low-pressure side caps. If you only need one set, please refer to the separate listing. Anonymous shipping via Yu-Yu Mercari. R134a Car Air Conditioner Valve Replacement Maintenance High Pressure Low Pressure