Grab hooks will lock your chain in place by slipping a link into it sideways. (Don't ever put the point of the hook into a chain.) Slip hooks may be usful when wrapping a chain or strap over it and around a object you want to secure to the bucket. I think an ideal set up would be two grabhooks near the outside edges of the bucket and a slip hook or maybe even two inboard towards the center of the bucket. As for size, the grab hooks should match your chain size. The slip hook size don't really matter much in the set up I described, I guess bigger would be better for me, it would allow a bigger strap end to be hooked onto it if needed. If your just using some type of adjustable strap, grab hooks wouldn't be of much use.