The total weight of the B2 is only 9 ounces more than the T2. The Most Awarded Atomic regulator virtually identical performance as the T2 with a Brass First Stage The B2 gives divers an close alternative to the all-Titanium T2. The signature Atomic breathing performance is nearly identical. The B2 is ergonomically designed to be the world’s most comfortable second stage just like the T2. The key difference is the chrome-plated Brass body of the B2 first stage, which is more economical without sacrificing performance.