Compared to Sulfate, Ferrous Fumarate is a higher grade than Sulfate and thus more expensive. Fumarate is well tolerated and better than Sulfate but slower in absorption by the bowel. While Ferrous Sulfate is well absorbed and faster, but with initial light intolerance (just in the beginning) and might cause constipation to some. Vitamin C should be taken with any iron product to enhance absorption. This product (Ferrous Fumarate) is sold here on eBay at a bargain price. I like it, anywhere else, the price will be much more higher.