Intellifeed instructions?

[Vegard]

I bought a Arsenal used and it came with a intellifeed halo, but I don`t know how to operate it? :p

Anyone able to tell who installed it?

http://i22.photobucket.com/albums/b308/invicta1/DSC00103.jpg

PS- Just slapped the VP trigger and no-rise on there, marker is a beaut.. Just need a little feedneck trimming on the halo.. :)