External Gas Struts$120 for a set of four gas struts (+ shipping) Replacement or stronger gas struts to help lift the camper roof. If you've put a bunch of solar panels on the roof, a cargo box, frequently carry boats, or just have noticed the roof is more difficult to open than you'd like, then these are for you. To tell what strength you currently have, look at the label on the gas struts themselves and check the code: Ends in 3754 20lb Ends in 3516 25lb Ends in 3517