I wanted the most basic looking Juliets just because of their raw appearance (and also so I could install the Ruby lenses to them :p). Very tight fitting with the 15 earshox, and I try not to stretch out the flex couplers for the long term. With my other Juliets, I always and am now required to use the 25 earshox, but this ended up stretching the flex coupler. The fit is identical between the two. No serial number on these. I ended up getting a very good deal on ebay on these.