Surefire Flip Infrared Flashlight Filter

I have one installed on my Surefire M500a and it works great.It is plenty bright enough in ir mode when viewed through my pvs-14.A huge positive is that in ir mode there is virtually no visible signature.The only drawback is that it is a little bit clunky going between ir and visible. The latch on the flip-up lens is easily released with your thumb nail (if it positioned on bottom), but the spring isn't strong enough to flip the ir lens all the way up (or at least completely out of the way of the visible light beam). If you want to quickly switch to visible to blind someone this poses a problem.I used a Surefire head which switched between visible and ir by twisting the bezel, but it had a distinct visible signature which is a deal-killer for me.I am perplexed by the other reviewer(s) one star rating. I can only assume the flashlight was not powerful enough. These are not meant for use on regular flashlights.P.S. I just made a modification using a blade and small file that makes the lens flip up far enough to clear the visible beam.If anyone wants to know how post a comment and I'll post instructions.