Washington, Sep 5 : Facebook rolled out a new update to its Slingshot app making the ' pay to play' system optional .

Slingshot used to ask users to send a photo before they could 'unlock' the one they received.

The update gives power to the users to choose whether they want to 'lock' or 'unlock' the photo they are sending to others.

A locked photo would require the receiver to send one photo to open it, whereas the unlocked photos would be open for users. (ANI)