Credit to @Sk8shodown for their original posts
Also can get with analog sticks for £5 here
Sony Playstation Official PSOne Dual Shock Controller, WhiteProduct Description
Based on the basic button configuration established with Nintendo's Super NES Controller, the PlayStation Controller comes with additional second pair of shoulder buttons for the middle fingers. The shoulder buttons for both the index and middle fingers implements two-way directional depth controls using the two sets of buttons. Grip handles make less stable grip from shifting the middle fingers placement to the shoulders.