The older L7 strap that was supplied with the EOS 1D X has been replaced with the EW-100DB. They're virtually identical. The version specifically supplied with the EOS 1D X Mark II is the EW-100DB IV.
The main webbing, which is backed by thin leather, is about 1.5 inches wide and 24 inches long. The tapered leather ends are about 1.5" long. The 3/8" wide connecting straps are about 12" long on either end. Since the end of the connecting straps must be looped back through the supplied buckles, the longest they can be used is about 9.5".
Versions of the EW-100DB supplied with many other EOS DSLR cameras have the model name included on them, but straps supplied with the 1-series typically do not. Other versions also tend to have a wider red stripe on the edge of the strap, but they are all 1.5" wide.