mercedes A CLASS boot struts gas springs Available Here. Whether you call them boot struts, gas springs or gas rams, you’re talking about the same thing. All these terms refer to the small black pneumatic rams that hold up your boot lid. When they are working properly, you don’t even think about them, but, when they start to wear out, you notice them every time you open the boot. Their failure is the reason your boot is suddenly harder to open or the boot lid seems heavier than it used to, and man can those things be heavy! Fortunately, with the help of some simple tools and out DIY video guide, boot strut gas springs are easy to replace.