K50 Clear is a standard greenhouse film. This 6ml poly is UV stabilized to provide a longer life for exposure to the outside elements and has anti-dust additives to keep dust and dirt from building up. K50 Clear has 92% PAR light transmission, this makes it good to be used as a second layer of poly. Fullbloom most often uses it as a winter poly layer, an extra layer of poly that aids in insulating your greenhouse, but it can function as your primary poly layer as well if you are on a budget.