very simple, lure ppl to buy or que 0.015, 0.02 is the syndicate who que big quantity some time ago, so don't think u want to buy 0.015 then selling 0.02. Then no long later big one will sell all 0.015 and even sell off 0.01, so who buy 0.015 end up have to sell 0.01 or 0.005.