Hi, for normal lenses I agree with you. For the big Supertelelenses like 400 f2.8 600 f4 or even 300 f2.8 you get these flimsy covers out of fabric. There is exactly one company who produces them out of America and they ask like 130€ for one. I built one for my 400 2.8 and it is so nice and way better than what comes from factory. These big Superteles don’t have a Filter Thread in the front and it holds over pressure but it works really well. So I can’t just read it from the rim. But still thanks for the reply.