That plug looks very similar to the plug end used on the PFO ballasts.......I know at one time, you could get the from a couple places, but not sure if they are still available....They were sold for people that didn't want to cut into the wiring on the ballast to wire to their reflector sockets....
Flower to the best of my knowledge the IceCap doesn't come standard with that plug end....someone correct me if I'm wrong...I had bought 2 new 1 a year ago from my source and don't have them on hand since I sold them, but they didn't have that plug end. The did have the short black lead as shown, but bare wires at the end. To get it to work with your existing fixture you will probably have to cut the end plug of the fixture and hardwire the 2 together......
Ahhhhh let me hold my horses!!!!!!!
Check the IceCap website....Again this is a couple years and not sure if they ever took off or are still in production, but IceCap there for a time being was building and selling (not directly) I will call them ballast boxes.....The boxes had switches "on/off" on the box, and all the electrical goodies on the outside. You had to mount your IceCap ballasts or what not inside and wire them inside the nifty little housings....I would check their site to see if they are still available, and that might be an option as well....If not PM me and I'll tell you were I might have gotten the plugs from and you can contact them to see if they still carry the parts......It was 1 of 3 places I buy from online, so let me know!!!!!!