Our Official Y1-Baseball is constructed with a full grain leather shell. The interior components hold up to rigourous play with dual cores and tightly wound string and wool. The seams are mid-height for improved throwing comfort and durability. Mid-height seams withstand the impacts of play much longer than high seams. Our baseballs also feature Grip Control. This gives the ball a slightly tackier feel to help improve grip for pitching and fielding.