I have a tent with a ridiculously heavy hatch on the back door. Ridiculously difficult. The pistons supplied exploded and originally I just copied the model number onto the blown ones. I don't know what happened there because they were so weak I had to hold them open and I didn't notice any noticeable help from them. Then they exploded, no wonder. So I got it right, measured the compression and extension lengths correctly, found the heaviest I could determine by weight, and these beauties were awesome. The hatch door opens with a gentle urge in the right direction and closes with ease. Now I don't hate my dome anymore.