It is the 220 mm "Road" cable. There are only two sizes: Road and MTB. The Road RE Cable is used on Vado/Como/Creo SL. The MTB Re Cable is for Levo and Kenevo SL, as these have very compact frames and need a shorter cable.
Your RE will come with a Zee Cage II (L) and a rubber band for fixing the Re Cable plug in place. Pay attention to a rotating slide at he bike side plug:
When the slide is rotated to the right (counter clockwise), you can insert the plub into the socket. Rotating clockwise (down) secures the plug in the socket.
Also pay attention how the RE has been originally mounted inside the Zee Cage II.
Did you order the RE Y-Cable as well?
Besides, the Warsaw LBS got as many as 15 Range Extenders:
-- Is it OK if I buy two Range Extenders? -- I asked.
-- You may buy all fifteen of them! -- the salesman smiled -- We won't sell them for a year!