Review (3/5): Great for orthopedic use - see UPDATE
These work very well for my application. My orthopedic surgeon recommended I buy shoes with heels to counter a problem I have flexing my foot upwards at the front. This makes it painful walking uphill and on steep hills I have to go up on tiptoe. Although many shoes have 'heels', they do not raise the heel much above the toe of the shoe. By attaching these to a standard pair of hiking shoes I am now able to walk much easier and without any pain.
They are advertised as size 14 (US) but they are actually slightly small on my size 13 shoes. Overall, they measure 3.4" wide, 3.5" long and give a lift of 3/4". They don't exactly conform to the shape of my shoe heel, but they work fine. They are easily attached using the nails provided and Shoe Goo, or similar adhesive. I used two G-clamps to hold them while the glue set. Several pairs of these heels have now stayed firmly attached and outlasted the shoes.
UPDATE (Sept 2021): Please be aware that the new supplier of these does not ship nails with them. The old supplier, Leather Care Supply used to ship a pack of the correct nails with the heels. The nails are hard to obtain elsewhere,