How to transform a target in weapon
Bicycle saddles are easy to adjust and easy to remove...
and thiefs know that...
I-Lock is a locking device you install once for all on you saddle tube to tarnsform it in a bike locker :
1) Remove you saddle from the frame, like if you want to carry it with you.
2) Put the saddle tube across the rear wheel.
3) Use I-Lock to fix the tube (and saddle) on a tube of the frame, in this very position.
Now, you saddle tube (still attached to the saddle) is fixed to you bike and obstructs the rotation of the wheel. This tube IS your locker.
You tube saddle is now used as a U-Lock (or a I-Lock in fact ;)