This is part of the OG Spec Mosmatic Nozzle Assembly. This is an MTM 1/8" nozzle that screws into the female outlet of the nozzle assembly.  You would use this to change the degree or orifice size. Currently, this comes in 25 Degree and 40 Degree with a variation of orifice sizes. 

The orifice is the size of the hole that dictates how much pressure you get. It is dependent on how much volume (GPM/Flow) your pressure washer outputs. I would recommend the 40-degree nozzle for washing cars.

Options:

Degree
This is the angle that water will exit the nozzle.
 
Orifice
This is the size of the hole that water flows through. This is what regulates the pressure output of a pressure washer. See the above chart to help with nozzle selection.

Specifications

Mosmatic Stainless Steel Nozzle
- ⅛” NPT
- 25° or 40° spray patterns