Kaiser...
I'm using the '20-WD' for the 'Standard' rear fender light. It also comes with an extra bulb.
I'm using the 100-HD for my 'Interstate' trunk lights. It is a splice in setup, and can be set to either the 'wig-wag' (side to side) flash, or 'flicker' (both sides pulse the same).
When running my trunk, the effect of the fender light and the trunk lights is great! I'v had cagers pull up along side me at a stop, and say 'Hey, did you know yer brake lights were flashing?'... Also, If I'm stopped at a light, in the dark (my greatest fear), I apply the brakes again, if I see a car coming up behind me, just to be sure they see me. Usually, that results in them stopping a full car length behind me

Good luck!
Black Dog