AVL 1.87% Ivermectin de-wormer. Controls large and small strongyles, pinworms, ascarids, hairworms, large mouth stomach worms, threadworms, and bots. Treats up to 1500 lb horses. Same Ivermectin as other brands, just a better price! Note: Within reason, Ivermectin is non toxic. Studies have shown that, within reason, the more wormer you give the more worms are killed. The 1,500 lb tube is great for our average sized 1000 to 1,250 lb horses.