What is the difference between the Re-Pop Switch (
The FX is a cheapy on-off switch that mounts direct to the dash panel with a large nut that threads down on the body of the switch. The cable that goes down to the distributor is made out of 12 gauge armored wire but still has the threaded end to screw into the distributor as original.
The ERM switch is a heavy duty switch that attaches to the dash panel the same way the original pop-out switch did. Your panel has to have that cup shaped piece crimped into it for this better switch to mount to. The switch is made to resemble the original pop out switch. The cable going to the distributor is made to look like the original style cable so all will look as original in the engine compartment.