As part of the Android Operative system, there is a restriction that blocks installing applications outside the Google Play Store.

If it’s your first time installing an App through gun.deals, you’re greeted with, "Install blocked. For security, your phone is set to block installation of applications not obtained from Play Store" message as you try to install. But how do we get there?

To allow app installs from gun.deals, follow this steps:

• Navigate to Setting > Security.
• Check the option "Unknown sources".
• Tap OK on the prompt message.
• Select "Trust".

That’s all, now you can install the Application.