I had installed this app one month ago.but I dont like this app.if you want to earn 2 dollars, you have to use this app for around 500days.yes
it is lockscreen app which shows you ad while you unlock your phone or tab.but daily earning is 4 to 6 carates.there is 2000 carats equals to 2 dollars.so this is very long process.
there is no other options for earning.
and you have to open this app daily for activate lockscreen feature.its not good.