i use braid backing on some reels, mainly the ones with fluro because i dont want to put a whole spool of fluro on. the brand doesn't matter, if i were to buy braid specifically for this is would likely be 30-40lb of whatever the cheapest braid was. i have never had a problem with braid slipping when used as backing. i have however had issues with straight braid slipping on some spools. what comes to mind is just grabbing a 1000 yard spool of kast king braid its like $30