Device for a vehicle window wiper arm and method for installing the same

Device (140) for a window wiper arm of a vehicle, in particular a motor vehicle, characterised in that it comprises a cover (144) and an accessory, such as a nozzle (142), which is rigidly connected to the cover, said cover having a generally U-shaped cross section and being configured to be applied and fastened to an end piece (28) of U-shaped cross section of said arm.