neutral filter for long exposure

I am very satisfied, it worked well. I use it for long exposures but I made the mistake once of the breakaway in Dubai and it was on the ground with small stones, not a finished floor, if you want ...... then obviously, there are now some small "round" who are at the shooting. For software, I erase. But I feel that despite being designed in several layers, today just by making long exposures on clouds, I noticed I rayures..pourtant attention..peut be is- this very fragile? Apart from this nonsense of having escaped once, I am nevertheless very careful and I will never have again dropped or scratched. I clean it, actually with a cloth and glasses fogging of my mouth.