The look z is their race binding, din 8-18. The 140s are din 3-14. The z is all metal and pretty sweet if you are really rough on your shit, but to ge honest they are a little overkill for most of us. Unless you weigh over 170lbs. and are going huge all the time, the 140's will be more than enough. Since looks don't pre-release like salomons, you don't need to crank the din up. I am 165lbs and ride pretty hard on look p10s and a din of 7.5 is perfect for me (they have only come off a few times, when they should have). My buddy has them and he has to have them at the low end of eight when he should probably be at 7 anyway. Unless you need the higher din, just get the 140s.