Pfizer - At twice the strength of regular Strongid C, Strongid C 2X (2.11 percent pyrantel tartrate) requires only half the regular daily dose. The more concentrated Strongid C 2X is packed in a smaller container which saves on shipping costs. Feed rate: 1/2 oz. per 250 pounds of body weight per day. A 10-pound pail treats a 1,000-pound horse for 80 days. Measuring cup included.