Top positive review
So good I bought it twice.
26 November 2016
Nice bit of kit, fits my Sigma 150-600mm lens nicely and seems to be very effective in taking the edge off strong UV light. The claims about thermal range seem right I have used the 95mm filter on my big Sigma lens in the frosts of winter in the UK and direct sunlight and 36 degrees plus heat photographing the Eclipse in Wyoming, there would seem to be a fair bit of scope for thermal expansion there and it neither crept nor rattled. I eventually bought a second one of these because the first one broke when the LowePro camera bag in which the lens was being carried was dropped opening the rear door on a hired SUV at Keflavik airport. Given that the bag was just shy of the 10kg hand luggage limit, the filter was the only victim of the incident and basically did it's job in protecting the front lens element so I can't really complain.
Some other filters claim to retain optical clarity / resolution, but I have not noticed any change in clarity or sharpness with or without this filter on the lens.