The CMR300i is the replacement for the CMR180i and is fully compatible for all installation of Intuition-LC and Intuition-PV 
The Owl CMR300i is the 3 phase, 3 channel transmitter used on its Intuition-PV and Intuition-LC energy monitoring systems. 
The CMR180i will also upgrade an Intuition-E system to LC or Solar PV capability (may need extra sensors).

If you are replacing an older CMR180i, you will be pleased that one improvement on the CMR300i is when changing batteries, you no longer have to follow the battery change instructions needed on the CMR180i. With the CMR300i, you can simply change the batteries.