Not affected by damp conditions, better fuel Economy, better starting. 

Easy to fit often only taking 5 minutes, no holes to drill, no complicated wiring, no need to get spark gap or dwell correct as this is automatic and best of all nothing bolted to the outside of the distributor. 

These smaller than a match box these units fit inside the distributor in the same place as the points, just 2 wires come out from the distributor to the ignition coil