MANIFOLDS TWO VALVE, MANIFOLD TWO VALVE BRASS An industry standard for countless years, the JB M2 series of manifolds features our full flow design for faster evacuation/charging. Coupled with an angled bar for better knuckle clearance in rotating the hand wheels, and the original free flowing dual O-ring sealing system, the M2 is the classic American made manifold. All of JBs brass manifolds are equipped with heavy-duty metal gauge cases for added durability.