Perhaps it's not a typical necessity, but if you're paying upwards of ?500 on cymbals, what's another few euro to help protect them? The material is rugged and hasn't torn after a good bit of use. I manage to fit two into a normal sabian fabric bag, with 22", 20", and 18" cymbals. No problems, issues and importantly, no scratches/ blemishes on my cymbals.
They do exactly what it says on the tin, protect your cymbals and prevent any metal on metal contact. Very happy with the quality of them and bought two sets which are as good as new after many gigs so far! Definitely would advise to get thaw for any cymbal bag or flight case