With us a wooden hatch is unilaterally stopped by this gas spring, so the relatively high value NM. A few years ago I had the gas spring already changed before, but he has not held long, so I was skeptical. I am happy now but very pleased that I have but changed it again, because this new "enhanced" model has been running from the beginning very different from the old spare parts. There is again strong enough to keep the hatch at the top but unlike its predecessor better dampened, so it is not unrestrained deflection off the stop - so we look forward every day on the new smooth running - 3 year Warranty's also.