Man, I used one of the ND filters that came in the FMC and it was super tight. I could not get it to completely rotate to the on position. Then when it came time to remove it was a @#$%&%$ b*&%ch to get it off. These things are a POS. I don't think I'll be using these anymore. Hopefully the variable ND's I have coming from Moment will be more user friendly.