The MOV devices fire at voltages over 50 V. Bypass capacitors help reduce any RF problems. Construction is "basic", to be charitable. The MOVs are rated at 1000s of A of surge current, but it's not clear if the wiring will handle the rated surge gracefully. The top and bottom plates, not shown, are secured by 4 bolts to the rectangular extrusion seen here. There is no "reliable" connection to the mounting tabs, which are on the bottom plate, except compression of the alumninum plates. For a more reliable surge ground, I am using the screw terminals visible at either side.
Compared with the Polyphaser devices in the coax lines, I worry that the rotor/SteppIR protection with the ICE unit is fairly weak. The upside is that the Rotor and SteppIR controllers are relatively robust, and in the worst case they can be considered "sacrificial". Still, a multi-stage spark gap/inductor/MOV system (similar to the Hyperlink DSL device) would offer more security, at higher expense.