These gaskets fit 1/4" flare and 1/2 ACME standard fittings. If you are doing maintenance on you unit it's a good idea to replace these as well as they become smashed over time resulting in poor depression on the schreader fitting causing low flow or restriction due to swelling.
Warning: This product may expose you to chemicals including lead which are known to the State of California to cause cancer and birth defects or other reproductive harm. For more information go to www.P65Warnings.ca.gov