As the name says, Unlimited Free VPN - Betternet is completely free, and it doesn't have any kinds of ads. The only thing you have to do to use it is press on the connect button, and a couple of seconds later you can connect to the Betternet VPN network.
Unlimited Free VPN - Betternet is a powerful VPN client; it's also lightweight and easy to use. It doesn't let you choose the country to use as a mask, but in exchange you can have a really user-friendly experience.
Requires Android 4.0 or higher