All currently-shipping Trimble Geospatial GNSS receiver models are available with some level of customisation. In general, receivers are sold with configurations corresponding to a particular use case—such as Base & Rover, Rover-only, or Base-only—which can be upgraded as your needs evolve. Please contact your local dealer for product-specific information.
Other products like the Trimble R750 and the Trimble R780 are designed to be more customisable based on a diverse range of applications. You can customise the options you need, such as constellations or dual/triple frequency tracking.