The following is a review I posted on Amazon for the Engo Blister Prevention Patches -- $15 for (4) large and (2) small oval patches.
As a runner who routinely covers distances up to 13.1 miles, any extra friction on my feet can lead to nasty blisters in short order. Even buying the exact same brand, model, and size of running shoe every time does not guarantee a perfect, friction-free fit; even if the four pairs you bought before gave you no problems. This was the case with my latest pair of Brooks Beasts.
Usually the Beasts fit me perfectly right out of the box, but this pair started talking to my left instep within the first 5 miles of my first training run (in mid-March of this year). Trying to power through with the typical runner attitude was not the best move, as after I had finished the 10 mile run, I had a full fledged blister. During the next week, as I let the blister heal, I ordered the Endo blister prevention patches after doing some online searching.
When the package first arrived, my initial thought was, "Did I really just pay $15 for this?". But then I gave them a try...
I followed the instructions on the package, adhering one large oval patch over the offending area, which happened to be right where the shoe's insole met the side wall of the she -- and my arch would catch on the built-up hard rubber base of the shoe. I smoothed out the patch as I applied it to the shoe, and followed it up with 20-30 seconds of blow dryer heat; and then I wore the shoes to help with the adhesion. That was 240 miles ago, and just today I finally had to replace that original patch -- I could feel that burning feeling after today's 9 mile jaunt, and after further investigation, discovered it had finally worn through along the insole / side-wall junction. For my running shoes, 240 miles is well over half the life of the shoe. I would consider that to be some excellent performance, considering what these shoes have been through in that time.
I can't say enough good things about these patches. The slick surface allows your foot to glide right down where it's supposed to go, instead of getting hung up on any edges. During those 240 miles, the patch never came loose at all, and I still have two more large patches left after the one I installed today (as well as all of the small patches). I highly recommend them.