I've had my Lock N Level for 6 years now, used pretty much every time we use the caravan. In lockdown it was on our drive for almost a year and never needed to be pumped up.
We always use a thick rubber mat under it when on site (a boot liner folded in half) especially useful when on hardstanding pitches with sharp rocks.
Nothing but good to say about the LnL, wouldn't be without it for our twin axle, and we can be level and legs down almost as quickly as our friends with their rather more expensive self levelling system.
at €499 + 39 for the connecting tube it makes the LnL look a bargain.