The Honeywell 3-Port Motorized Diverter Valve Body V4073A1039 is a compact brass diverter valve bodt designed for use with zoned Heating & Hot Water.

For when poor system water quality causes seizing or blocking of the valve waterways, causing frequent motor burn out.

The brass ball body can be replaced (after system isolation) without disturbing the connections on the pipework.
This can be useful when the original install is fixed tightly with no disernable movement available on the pipework which can lead to damaging pipework or connections