The Laars Heating Systems FT1861 Cascade Communication Cable is an OEM wiring component designed to connect compatible Laars FT Series boilers for cascade operation. It links the control boards of multiple boilers, allowing the leader unit to communicate with follower units for coordinated heating operation. The 60-inch cable includes an ending resistor for proper system termination a... https://www.partshnc.com/laars-heating-systems-ft1861-cable-communicate-cascade