https://www.youtube.com/watch?v=mIJnUuIhy-wI have used the Nisi Filter System for over a year now and think this is the best system out there.To start you pick up the V5 Pro kit for $180 - I recommend you purchase from B&H Photo This includes a nice protective case, high-quality circular polarizer that is integrated into the 82mm ring, the filter holder and adapter rings (that allow the holder to be used with lenses that have 67mm, 72mm, or 77mm front filter threads. Additional rings are available for purchase)I recommend you add:

• Nano IRND 1.8 Filter (6 Stop) [Buy from B&H Photo]
• Nano Soft-Edge Graduated IRND 0.9 Filter (3-Stop) [Buy from B&H Photo]

The 6 stop allows you to easily do long exposures in cloudy conditions or near sunrise/sunset. If you want to achieve long exposures in bright conditions pick up the Nano IRND 3.0 Filter (10 Stop) [Buy from B&H Photo]  The Nisi V5 Pro holder is their latest edition and it's improved over the original. Earlier models were very difficult to slide the glass plates in/out of and this updated version is much better while still holding them securely in place.Advantages of Nisi over LeeThe NISI system comes in a nice leather carrying case everything is protected and a silent soft magnetic latch makes it easy to access. Downside - it is a little bulkyNisi offers an integrated circular polarizer often times when I'm using these filters I'm photographing water and I do want to use a circular polarizer to control or cut the amount of Reflections and it's so easy to rotate with little dials on the edge of the filter holder.The Nisi system comes with a variety of adapters that allow you to use it with lenses- 67mm, 72mm, 77mm, and 82mm Adapter Rings. Additional adapter rings are available for purchase. Quality - Extremely sharp and no color casts. I found the Lee system to have strong cool or blue color casts in their stronger ND filters. Why do I recommend the NISI system over stacking several circular filters?

• Flexibility- this system allows me to use graduated filters AND circular polarizers together and easily.
• no vignetting even on my widest lenses.