View Facebook Private Profile Picture Large

Have you ever wanted to add an old friend and you don't know if this is his account and you cant view his   
?profile picture because his private setting cant allow you
now i'm going to teach you a trick that will let you view the picture in a larger size

first open the target profile 
then copy the image's url as shown below

Then Open The Url In in a new tab by right click and then paste
Now change the value of the image from s160x160 to s720x720 or try s360x360 if it is not clear