Only my opinion, but breathable groundsheets are a total waste of money. After a couple of days the grass grows through them and, it the ground is at all damp, you even get wormcasts sprouting through. I think nothing is better. I always use a real groundsheet and, yes, the grass goes yellow after a week. But it never lasts long and soon greens up again. [There, that will get all the open-toed sandal brigage banging on their environmental drums.] If you are detemined to get a breathable groundsheet, try mail order - www.towsure.com and follow the link to caravanning - groundsheets.