I am a HUGE fan of Breakthrough Photography filters and it's all I use now, except for some graduated filters that they did not make until recently.I'm not the best at caring for my filters and I have noticeable scratching after a LOT of use but I have yet to notice it in the photographs. I really cannot wait to upgrade to their new square filter line of filters anyway so this is just a placeholder.After having this for a while and loving the results (very little discernible color shift) I purchased an X2 polarizing filter. The first time I put it on I could not get the two to come apart. I froze them, I put rubber bands around each of them to no avail. I finally gave them a shout to see if there was some secret I was missing but they said I've tried everything that they would recomend. Now is where it gets really great. They sent me a new polarizing filter and a new x2-6 stop ND and a return label for the one I sent back.Once I received the replacement I thought I had the same problem because I could not get the things apart again. But...I discovered a secret (or common sense?)...you have to very gently hold the filters to loosen them. I don't know how else to describe it other than just a light grip, not a firm grip. I'm afraid this may be the same problem I had with the first ones but I've never experienced anything like this with other brands of slim-line filters.There's absolutely nothing wrong with it and the slim nature of the rings are part of what make this awesome (A lot more stacking!) I just wish there had been some type of "instructions for morons" included with the filters. I never had any problem with my old polarizing filter and the Breakthrough ND filter but the Breakthrough Polarizing filter is also much slimmer.So just in case you think your Breakthrough Photography filters have bound up just relax your grip to the point of almost dropping them and turn. Don't worry about turning the polarizing ring just gently hold and turn and viola they will release...it's very bizarre but they come apart just fine. I'm sure everybody at BP had a great laugh or "what the hell is this guy talking about" moment when they received the return...Once I go with their new square filters, graduated, and also their ND + CPL I'll get a review up for those but I expect great things from them.One last note/rant/whatever, I would also like to see comparisons between the X1, X2, and X4 series. They show plenty of comparisons between BT and other brands but I went with the X2 because there were no side-by-side comparisons of the significantly more expensive X4 line. If I had a better explanation and visual side-by-side comparison I would have spent the extra cash and gone with the X4 line (which also has brass rings and I probably would have saved myself some embarrassment). I'm also pretty sure I wouldn't have the scratches I do though because I have since had the chance to try a 10-stop X4 ND and it seems to be a significant upgrade, much easier to grip, and the glass of course is phenomenal...but the new square filters they may or may not sell someday is made with tempered SCHOTT glass so I expect it to be great and easier to manage, aka, drop...Did I mention I'm kind of excited for the square filters?