The Genustech ND 0.9 filter is a 3 stop Neutral Density camera filter, ND filters are invaluable to when you need shallow depth of field in bright lighting conditions. Great for long exposure photography and creating motion blur. This ND filter id 52mm in diameter.
Ideal companion for your Genus GoPro Cage. ND filters on GoPro cameras helps reduce "jello" effect in GoPro footage as it lowers shutter speed. Lower shutter speed also increases motion blur which makes your footage look more cinematic.