This is the kind that I used, gray with paper backing. I found that if you're using a fairly long piece of the butyl tape that it is best to leave the paper backing on it for as long as possible as it is very easy for the tape to stretch and lose its shape.The stuff from the link I posted is gray and comes with a nice thin paper backing that is very easily removed. I have bed tracks and other hardware with it and it works perfectly.
My cockpit is full of fastener holes I have yet to fix. I just put little squares of butyl tape over them until I can fix them.