Receptacle Cover Orientation

[Tinwoodsman]

I purchased a M-Series receptacle cover shown below. I had planned to install it with the cover flap lifting up but the writing on the cover plate is upside down when installed that way. Is it supposed to open up or down?

 

[gimpyrobb]

That is the correct orientation to mount it on a deuce. If you look at the trailer plug, there is a slot that lid lines up with and it acts as a "catch" so the plug does not slide out of the plug receptacle.