Heel and sole lifts can be done on Birkenstocks in either cork or soling material. The height of the lift will limit the height of the cork lift available. Cork lift adjustments require a new sole on the adjusted sandal. There is no limit on the heght of the soling material lift. You will need to send in a copy of your RX from your doctor indicating amount of lift, height of lift and whether it is heel only or full sole. Free shipping only in the USA. This is for one shoe not a pair.