Granite II Vest - ReversiblePowered by 37. 5 insulation, the Granite Reversible Vest is packable and ultralight. The key feature of 37. 5 insulation is its ability to make you comfortable, which ultimately helps you perform better. When you are cold, it warms you, when warm it cools you. 37. 5 technology removes moisture before it turns into sweat, helping you maintain an ideal core temperature so that you can perform your best. Climate control clothing with 37. 5 Technology has