Rinnai REU-MSB-C1 Manifold Electronic Cable Thing The Rinnai REU-MSB-C1 Manifold Electronic Control System Pack B (MECB04) is put together to let you link up multiple Rinnai tankless water heaters in a multi-unit installation, so communication between the units is super smooth. You can use this electronic cable with the REU-MSB-M Controller Kit to connect all the way up to five Rinnai water heaters, making sure they all work together perfectly and in sync, and your system goes as smoothly as possible too. If you've got a big operation or a household that needs lots of hot water, then the REU-MSB-C1 is perfect for you. It makes sure your units work in balance with each other to keep things running smoothly and that everyone in the household has got the hot water they need. This is especially g