Yes these are for grass clipping & yes I plan on side discharge/mulch whenever possible but it makes far more sense to have a 6 foot x 6 foot burlap squares to dump clippings onto then tie corners than to struggle with plastic trash bags unless it's left at the customers curb or at their trash barrel. And no I'm not going to dump clippings in the back of my enclosed trailer or my truck bed. Huge PITA. With all that said . . . what is the best size of burlap square to use 72" x 72" or possibly bigger 96" x 96" maybe smaller 54" x 54"? Also do you use 7 oz or 10 oz burlap? Treated or untreated? Also a good online source that doesn't require a $100 to $150 minimum purchase would help?