The boys' now got 13 days in the park and maybe 20 days of pedalling in the two months he's bought them. We machined wash them (no dryer) twice now. They still look perfect. First pads he's had that haven't slipped. He's a pretty skinny kid:
http://7protection.com/product/flex-knee/
Got them at "Fun For Kids" in Whistler at the entrance to the Hilton in Mountain Square. They usually give a locals discount as well or a discount for kids in a winter race program for us fake locals.