: "Exclusive" software downloads frequently contain spyware or adware.

: Non-friends can only see a small, low-resolution version of the current profile and cover photo.

When someone locks their profile, Facebook applies a "limited view" for anyone not on their friends list:

Exclusive Guide: Understanding "FB Locked Profile Cover Photo Viewer" Tools

: Many of these sites require you to log in with your own Facebook credentials, which can lead to your account being hacked.

: Using automated scrapers to access private data violates Facebook's Terms of Service. Legitimate Ways to View Public Content

: The option to click and view these photos in full-screen mode is disabled for non-friends.

If you need to see a cover photo that is still public (even on a restricted account), these are the only safe methods: Lock your Facebook profile | Facebook Help Center