Megger BAKER DX R PPI 4 is a portable protection relay test set that can test a wide range of protection relays, including overcurrent, earth fault, distance, and differential relays. It is a compact and lightweight test set that is easy to use and transport. The BAKER DX R PPI 4 has a large color display that makes it easy to view test results. It also has a built-in help system that provides information on how to use the test set.