This is the lid support for a variety of applications! It is convertible since it can be installed on either horizontal or vertical, for lids or drop fronts. It is reversible to be mounted left or right, and change tension direction from lift-up to drop-down as needed.

It's adjustable: Lids or drop fronts up to 20lbs can have their tension easily adjusted using a number 4 Allen wrench (allen wrench not included). The angle opening can be set at 75 degrees or 90 degrees depending on how brackets are mounted. It's even demountable: Brackets can be mounted without the support arm attached, and the support arm can be removed! Lid or drop-front requires separate hinges.

We used one of these to support the wall mounted bathroom vanity mirror in a 2016 Airstream 27FB model travel trailer.  It worked great (was able to support the mirror in the open position easily). 

Lower seam on the packaging is partially opened but all package contents appear to be all present.