Burlap

40" width, 10oz wt. Both Jute and Synthetic are available.  Sold by the yard or roll.  This product is mostly used to go over the spring system on the decks of furniture.  The burlap prevents the padding layer above it from entering the spring system.  Generally applied with 3/8" staples.   Pro Tip: The synthetic will stretch out over time but will never dry rot.  The Burlap is less expensive and will generally last the lifetime of the furniture.