Have some of the specialized insoles, been using them for just over a week, at first they felt like a pebble in my shoe, now they feel better than the best pair of slippers, very comfortable. Had no idea I had no arch support, but they have a funky little matt for you to stand on, which shows up how your foot is. Used to rub my knees on the frame at times, with the occasional knee twinge, no more rubbing and not had a twinge since. Might be worth getting measured, £20 seemed steep for an insole, but the extra comfort now used to them is worth it.