I reckon they are all more or less the same if you have a steady dog they all do the job really I've owned most of them and the old pieps box is the best thing I've owned it's been smacked with spades the plastic cover broke I glued a plastic cover over it back filled her twice and got her back it's got a full roll of black tape holding it together and it doesn't miss a beat anyway I don't think there's much difference....make sure it's not the dog moving before you shell out a fortune lol