Jasper got a medium for his first, which lasted about 6 weeks, the next medium lasted about a week and so we've now got a large which is still going strong after 6 weeks despite his best daily efforts! Strange how some love them and some can't be bothered with them! It's probably the only thing he bothers to chew now, that and his nylabone (and thankfully not the skirting board any more lol!)