Hi all, I had 3 questions - sorry if they've been asked like a thousand times: 1. Omni (tennis) shoes, what are they exactly? Omni implies for everything - but I gather it's mostly for (artificial) grass? 2. Those omni shoes for artificial grass/astroturd (with pimple-like sole instead of herring-pattern), can they also be used for clay? Or is that seen as bad and/or unsuitable for the clay surface? 3. I regularly play on clay, artificial grass (or sand with artificial grass would be more correct), and hardcourt (or more precisely, concrete). What would you guys recommend, shoewise? I'll probably need more than one pair? (By the way, the concrete is rather bad for the joints I think. Should I get a pair with air for that or doesn't that help? Or just use my running shoes?) Cheers!