Parallel Set - GripFAQ.com

Parallel Set Watch the Video - Gripper Parallel Set (WMV): Click Image to Enlarge

Note the position of the handles relative to the palm and the pinky.

Parallel set refers to placing the gripper in the hand such that prior to the close attempt, the handles are parallel to one another, almost an inch apart. This is achieved by pressing one gripper handle into the crease of the palm closest to the fingers and pinching the other handle down until the fingers are wrapped around it at parallel. The pinky should be halfway off the edge of the gripper handle. Closing a gripper with a parallel set it the first step to mastery of the gripper.
In order to maximize power of the parallel set, it is important to have strong thumbs on both hands. The thumb on the closing hand can be flexed prior to setting the gripper, providing a wall to hold the gripper handle in place on the crease of the palm. A strong thumb on the setting hand is essential to being able to bring hard grippers down into the parallel set position.