What you do is have a duplicate key made, then you have to cut the top off of it and trim it to fit in a slot in the back of the skull (they have other options as far as designs) and then a set screw holds it in place. Then you fill the area around the key where it goes into the knob with JB Weld, let it six for 24 hours and PRESTO, you have a custom looking key. So yes, it does replace the key so to speak and a key is still used to start the bike.
Very clever! When you go inside to pay for your gas and forget your key in the ignition it just looks like a cool fastner and not a temptation to someone else lusting for your ride. Not that you or I would ever ....
I love the items from x-cessories.net and have used the key holders on both of my VTX bikes and now the Fury. You should look at the "dots" they have, too. I find 2 or 3 places to put them on my bikes.
True story...the first time I used the key fob and took the bike to the dealer for service, they had to call me to find out how to start the bike. So, I feel fairly safe leaving the key in the bike for short periods of time.
Kenny is great to deal with...give them a try.