Most clicky Cherry MX-type switches have a tiny nub on the left edge of the slider that hits the top of the clip and reduces key travel. Clicky switches from Cherry, Kailh, Greetech, Razer (Kailh and Greetech), Outemu, Switch Master, Trantek and Zorro have them.
Gateron's clicky and Aristotle switches are the only ones I have seen that don't have them.