Is an 'O' ring on a push fit fitting made from neoprene?

An 'O' ring on a push fit fitting can be made from various materials, including neoprene, but it is not exclusively made from neoprene. Other common materials for O-rings include nitrile rubber, EPDM, and silicone, depending on the application's requirements for temperature resistance, chemical compatibility, and flexibility. Neoprene may be used in specific applications, but it's essential to check the manufacturer's specifications for the exact material used.