T Hose fitting of nylon plastic.
T hose fitting in several different sizes. These couplings are for joining 3pcs hoses with the same internal diameter. Eg the installation of an external boost gauge can make a detour to an existing vacuum hose with a T-junction.

Also fits very well to replace any original T-connectors on the car when they are getting old and cracked. Can be used in most areas, such as fuel hose, radiator hose, oil hose, etc.