50% Grey Layer Action
Download the Zip file. Unzip and locate the .atn file in the download directory. Save the file to your folder in a place where you can locate it easily.
In Photoshop go to the Actions Panel (Window> Actions) and open the menu in the upper right corner of the panel. Find “Load Actions” from the menu and click it. You’re given a load action dialog box. Navigate to the downloaded action and click “Load.”
You can also save your downloaded action to your default Photoshop folder which is in C:\Program Files\Adobe\Adobe Photoshop\Presets\Actions.