At the side of the box, there is a small metal piece with a unique ID and a code above it. And it was much more expensive then on Amazon. I used this riser block along with a vintage Cycle Ops bicycle Training Stand and it does a beautiful job of maintaing a nice level bicycle position. DL APO and Peace for a free EQ application. I Absolutely love them shoes will buy again LTE Discovery App was showing me an active and full LTE connection in my area for my provider (metro by t-mobile) but phone could not connect to it, only EDGE works. These slippers are garbage and anyone buying might as well just send a donation because you get no value for your money. The charging port is under a cap and well hidden from any moisture, so Im confident sweating at the gym or running in the rain wont bother it. 5 and 7 for comparison. The plastic see-thru top is nice.