I dont remeber exactly where I got them Bue ,I will look it up if I can find it ,I do remember they where pricy hard to come buy but the guys that make a lot of these bows tell me its as good as sturgeon bladders just not the historical type but nether is Ea-40 for horn all though Adam Korpowicz recomends it , Im lucky enough to have friends that make these so if I get in trouble I can make a phone call but a lot of prep before you even start building !