Not working
Will not change size of square tube, even after paying for app
Yes, Hollow_ is completely free and it doesn't have any in-app purchases or subscriptions.
Not enough reviews to make a reliable assessment. The app needs more user feedback.
Hollow_ is free.
To get estimated revenue of Hollow_ app and other AppStore insights you can sign up to AppTail Mobile Analytics Platform.
Will not change size of square tube, even after paying for app