The reflective surface looks very different from the STL-V2, V6 and X9... It doesn't appear to have a flat area immediately surrounding the LED, and it doesn't look like it has a plastic piece that centers the reflector around the LED....?
I believe that's a misprint. Calculating from the battery tube (which is about 24-25mm probably) the head is 57-58mm. It's a similar light like my Ultrafire X5, with a similar dropin, maybe better quality.