Our WonderPana ND16 + ND32 kit is great for creating quick and simple long exposure photographs. These are also some of the most popular and versatile neutral density filters, so it only makes sense to bundle them together. Both filters for the 145mm WonderPana system are double threaded, meaning that the front of the filters have a 145mm inner, or female, thread for stacking multiple filters. These filters are also kept slim at only 7mm thick. There are also ultra-slim options available for many of our 145mm WonderPana filters. Ultra-slim variants are 5mm thick and do not offer the front, inner thread for stacking. One thing to note is that we only offer ultra-slim ND filters for our 186mm WonderPana XL system. By utilizing the double threaded design mentioned above you can stack your filters which offers 9 stops of neutral density when using the ND16 and ND32. This means you can slow down your shutter speed drastically for more dramatic, epic long exposures (if you are into that) m...