 The sidemount diver has to swap regulators at planned intervals to ensure that the use of gas is balanced from both cylinders - thus ensuring good balance and trim in the water, whilst preserving a sufficient supply of air for emergency sharing.As of 2013, the only sidemount system offering a manifold system is the UTD ‘Z-Manifold'.This equipment provides a link between cylinders and dispenses with the need to swap regulators and balance tanks.