As described on the back of the Clock Tower manual:
"The ASCI Grip is a one handed controller designed for the original PlayStation. The ergonomic design incorporates a one-piece directional disk that will comfortably fit both left and right handed individuals.
The Grip features a supportive rubber cushion on the back for added support and durability. The button layout is arranged so that every button you will need is at your fingertips.
Plus, you can customize the Grip to suit your favorite game by using one of the 3 pre-programmable configurations, one of which allows you to program trigger buttons.
This is the ideal controller for RPG's and strategy type games. Now you can move, pull off combos, and wonder what to do with your free hand all at the same lime."