[Brass] I wanted a 3 stop ND 112mm filter. I found Tokina is really good. I love it and it does perfect pictures.

[Brass] 4 stop ND but as advertised. Know exactly how many stops used rather than VND with imprecise wheel.

[Glass] High-quality ND instead of VND

[Solid ND] Its almost magic. Se what your eyes can't see. Thats what this filter does in a full conversion camera, a tripod and a photographer capable of working with tools that are not for everyone. But if you pay what it costs and wait for it to be back ordered you are more than likely a committed photographer already. The filter can be used in a lot of scientific uses but I got it once I converted a full frame DSLR with still a lot of life ahead to full spectrum and got a very large set of filters to get the most of it shooting infrared and UV photography. So far it's been a great way to open new possibilities on creative photographic exploration.

[77 mm] After long ago exploring IR images with Kodak chemical films, I purchased the Kolari K665Pro and K720Pro to use on a stock Canon EOS 5D Mark IV and Canon lenses. I chose the Kolari Pro series for their sharp cutoff spectra as well as their filter coatings compared to Kolari's base series or Hoya. The Kolari Pro quality / performance / price point trade-offs were great IMHO. Starting with the 665, I set the camera for manual exposure (typically bracketing around +2) and manual focus (typically longer focus settings), and the stock sensors pick up enough red for good composition and control. It has been a short learning curve and I am most pleased with the images that the Kolari filters are generating: awesome black and white landscapes, cloudscapes, and waterscapes, and excellent starting points for post-processed color shots (native red hue or channel swapped)! No discernible color aberration until I push the image magnification to its pixel limits. The coatings have been great with tough lighting angles - no flares - and stay remarkably clean in windy, dusty environments! Continuing experiments with the 720, which pushes the limits of the stock sensors but still works well. Highly recommend the Kolari 665Pro for anyone getting into IR!!!

[Solid ND] Great to have a non-variable ND option for Canon drop in filter style.

[Brass] I really like everything except I needed to order a larger size to fit a circular polaizer.

[77 mm] Filter really makes a bold difference in astro imaging. Noting that the lens sun hood doesn't fit over the knurled edge of the filter. I can live with it since a sun hood is rarely needed at night... if I were to use this filter for artistic reasons during the day I might have another thought

[77 mm] This is not a filter to have just for fun. First of all it requires you to have a Full spectrum conversion on your camera. Second of all it is for a very specific use and its price is no joke, so if you don't need it I would spend my money on something else I would use more. But in my case it's been a blast. I will use a lot more my converted camera now that I have it, and just getting started with experimenting out of the users manual I have a lot of ideas to work on with this filter.
The filter only lets through UV light so exposure compensation is required and even under bright sun you will more than likely shoot on a tripod, with high ISO using slow shutter speeds. This filter is a tool, not a toy.

[77 mm] After long ago exploring IR images with Kodak chemical films, I purchased the Kolari K665Pro and K720Pro to use on a stock Canon EOS 5D Mark IV and Canon lenses. I chose the Kolari Pro Gen series for their sharp cutoff spectra as well as their filter coatings compared to Kolari's base series or Hoya. The Kolari Pro quality / performance / price point trade-offs were great IMHO.

I posted a review of the 665 and can not say enough positives about it!!! 5 stars!!!

Still experimenting with the 720. It is slightly more technically challanging on a stock camera, but just as impressive as the 665 so far. Highly recommend the Kolari Pro Gen series for anyone getting into IR!!!