ND64 Square Filters (1.8/6 Stops) 100*100mm Optical Glass Neutral Density Gray ND Filters Ultra Slim HD Nano-Coating Waterproof & Scratch Resistant

SKU: KF01.1146

are these filters glass or plastic? How many filters can it hold?
Answer Question
It came with the 10 stop glass filter and seems to be pretty great quality. I'm loving using it. Even ordered a 6 stop to go with it.