Gas struts or springs are used in caravans and RVs for helping to lift and hold heavy things like the window shades or the roof of a pop-top or even lifting an island bed for storage.
It is important to use the right gas strut as there are many different varieties.
Important factors to consider are strength extended length and compressed length.
All of these factors are important to the correct installation and working ability for the job they meant to do.
Other things that may be a choice are the Shaft size and the Ball Joint size. The most commonly used ball joint on RV's are 10mm.