The cover itself is fairly waterproof and made out of good material. The bungee application didn’t work for me because: 1) the bungee edges were sharp and not rounded out, causing there to be great potential for it to scratch up the unit. 2) my ac unit has a panel access in one of the corners so there is no grate to grab. Ended up taking some rope and running through a drilled hole in a piece of 2x4 on each corner. Holds down the cover great.