Wire hay balls, I thought they were useful holding the hay in them, i never thought one of guinea pigs would get caught in it. well some how one of the wires came a little loose and i didnt notice. One of our guinea pigs got caught in it. she must of pushed aside the loose wire while eating the hay and pushed her head out the other side. Lucky we were home and were able to get her out with in minutes of it happening, before she did any damage to herself. I will be going out and buying a hay stall for the side of the cage. I am really just writing this post to Warn others what happened to my Lionnie ginger. I would hate to have think what would of happened if we were not at home. I know most pople on this sight proberly know this i just wish i did before i used one in the cage. What is the best safest kind of hay rack/stall to buy???