They strongperfect for a quick use.Just what i was looking forThe ballies are fine for what they are but the sharp opening edges will tear up the elastic in no time.Buy an extra roll of that to replace it.I was a little skeptical purchasing these however they are bettee than similar items I've ordered from other sellers on amazon. Will order again.Several have broken and once used they stretch out.We got one wear out of these knocker balls - the pearlescent color all flaked off! Very disappointed.