I rotate them so I know which is which. Failed after a week. They are comfortable and provide excellent arch support and stability. It is very comfortable and that is an absolute requirement for any headset that I use. I got for pool side wear and support the is decent. With EQ the HD660s can be made to sound better but are further away than the HD650s to the 1990s. I have bought several ?orthotic? flip flops, trying to find the right one for my newly irritable feet. This a great outdoor speaker and can go pretty much wherever you want it. it?s hand wash only. Incredible kids hiking shoes.