what is this please !

[zippy]

Hi got my car back after a small power steering fluid pipe change and just noticed this is missing ? Can anyone tell me what "this" is please ?
Sorry to be a muppet...pic is not of my car by the way for obvious reasons

[Nobby]

Just loads of electrical connectors and the rest of the power steering reservoir

[zippy]

thanks .....phew.....looks like they just forgot to put the cover on after replacement of power steering pipe.