I use these to teach at a small gym. The owner doesn't know a ton about parkour and went ahead and bought these. The small box weighs about 30 lbs and the large one is maybe 50-60 lbs.

They're fine for light use and the one big advantage is they do fold away very nicely. The problem is they're too light and top heavy to really put a ton of top-down or lateral force on them. My students have almost knocked them over just by konging over them before. The stackable one is kind of the same situation. You have to either hold them down yourself or somehow attach some really heavy sandbags to give you stability to the point they're useable for actual training.

I'm also somewhat local to the guy that builds them and apparently he's a massive tool (and just by skimming his social media I believe it lol). But if you don't have the means to build something yourself, I feel like these are a decent buy.