Boot strut gas springs, also known as gas struts or gas lift supports, aid in the opening, closing, and supporting of various compartments like the trunk or bonnet. These gas springs consist of a cylinder filled with compressed gas (usually nitrogen) and a piston inside the cylinder.
When the boot is opened, these gas struts extend and support the weight of the boot lid, making it easier to lift and keeping it in an open position until intentionally closed. They work by using the pressure of the compressed gas to generate force, which helps counterbalance the weight of the boot or any other hinged component they're attached to.These gas springs offer a controlled and assisted opening and closing action, providing convenience and safety by preventing the abrupt dropping of heavy lids or hatches.
Boot struts, boot dampers, gas rams, gas springs or boot springs - all different terminology for the same thing. 
Essentially, they're the small black pneumatic rams that hold your boot or tailgate up when you open it. You might not realise it but they are also helping to lift the boot/tailgate when you open it, which is especially important on hatchbacks and estates which can have very heavy tailgates. Over time, boot struts can become worn and loose effectiveness, which will manifest itself in a boot lid that won't stay open, or is extremely heavy to lift. Now, that might not sound like a big deal but it's actually really annoying to deal with when you're trying to load things into the boot, especially if you're manhandling babies, buggies or shopping at the same time. The good news is they're cheap to replace and you can do it yourself in a few minutes with some basic hand tools.
Check out our DIY Boot Strut Replacement video below: When you're changing boot struts always get someone to help you hold the boot lid open rather than using a prop or support, you could do yourself some serious damage if the boot lid comes crashing down on you! Despite there being thousands of different boot struts for all the makes and models of car there are only a handful of different types of fitting on the end of the strut and the vast majority of cars use the type featured in our video. So how do you replace them?
Step 1 Get a helper to hold the boot lid in the fully open position. Take a narrow, flat-head screw driver and insert between the boot strut ball socket housing and the metal retaining clip and gently prise the clip open. 
Take care not to slip with the screwdriver as you could damage your paintwork. Repeat the process and release the retaining clip on the other end of the boot strut then remove the whole thing. It may need some gentle leverage to separate the ball joints.
Step 2 Push the new boot strut onto the ball joints and push in the retaining clips at both ends ensuring you mount it the same way round as the one you just took off.
Step 3 Repeat the process for the other side. **Note** Never be tempted to grease or oil the ram on the new boot strut, it doesn't need it and will do more harm than good.
