Do you mean to go on the walls of the stable ? Fieldguard do a kind of rubber strip which you can put all round the stable so that if the horse gets cast it has something to push its feet against to get up.
Or if on the horse - just buy an anti cast roller available from any saddlers.
A tip I came across once (and have used!) suggested using spare bales of straw or shavings round the sides of the stable. This has two advantages : 1) your spare bedding is already IN the stable so you don't have to lug it around; and 2) they are solid and act as a wonderful "bank" in the event of the horse getting cast. Conventional banks are pretty well useless unless they are halfway up the wall (just watch how high your horse's legs get when he rolls!!). Always worked for me!!!