Made from Buna-N rubber to provide superior resistance against abrasion and water swell. Assortment contains: 2 of each Model No. 35721B, 35724B, 35725B, 35726B, 35728B, and 35729B; and 1 each of model No. 35738B and 35739B. See Related Items. Black. 1 assortment per card.