Greenhouse grade. Easily used in drip line systems. Not to be used as a foliar feed fertilizer. White granular pellets devolve easily in warm water. Should be stored in a air tight container or you will end up with one, big, white, rock.
As of 1978, only 170,000 tons/year were produced for applications in fertilizers. The fertilizer grade (15.5-0-0 + 19% Ca) is popular in the greenhouse and hydroponics trades; it contains ammonium nitrate and water, as the “double salt” 5Ca(NO3)2.NH4NO3·10H2O. This is called calcium ammonium nitrate.
A $ 13.65 flat rate box holds 4-5# bags and ships anywhere in the US