I was worried that this was a knock off seller but, it was the real thing. First of all the delivery was very fast. It took 8 days from the day I ordered it for me to receive it (from Germany to New York). It is true to size if you are familiar with your own feet. I am a size 8/8.5 depending on the shoe type or brand. Under no circumstance am I any other size, so when a shoe is not offered in a half size I automatically know I'm an 8. Its also good to be familiar with your European size and for me it is always a 39. That is what I ordered and they fit perfectly. The people who complained about the size maybe didn't adjust the straps. On the Birkenstock website it states how the shoe is supposed to fit, "your feet should be nestled in the footbed. This means that they should not rest on the inside and outside of the footbed edge. Just as with a regular bed – you don’t lie on the edge." The people who complained about the material not being leather should have referenced the real Birkenstock website and be aware that some of the colors in this style are real leather and some are not. I got the Mocha color and the website states "Birko-Flor - durable, synthetic upper material with a leather-like finish and soft backing Birko-Flor nubuck is made of easy-to-care-for and hygienic PVC, which has been lined on the inside with a soft, breathable layer of fleece. The surface looks like nubuck leather. This high-quality material is very gentle on the skin and comfortable". If you are familiar with Birkenstock you can trust this seller to deliver exactly that. If you are not familiar with Birkenstock I suggest you familiarize yourself with what they offer through the website and visit a shoe store and try them on. Finally, these were EXTREMELY comfortable, I've never had a more supportive shoe.