Nozzle

noun

1. A short tube, usually tapering, forming the vent of a hose or pipe.
2. A short outlet or inlet pipe projecting from the end or side of a hollow vessel, as a steam-engine cylinder or a steam boiler.
3. The nose of an animal; muzzle.
4. The part of an earbud that accomodates eartips.

   "The shape of the nozzle prevents the use of aftermarket eartips."