They were very fragile and we probably broke 20% of them when trying to fill them. However, we didn't get past half of them at the birthday party and they definitely served their purpose. I won't complain too much about how brittle they are though, as getting hit by a water polo that's too strong can be quite painful! They were great for their value and what we needed them for. As someone else mentioned, the jets are complete crap and they have a lot of plastic caps. I just melted them down with a lighter. They were easy to smooth out. So it really wasn't a problem.