The 338 is fitted between tripod and head and is used in combination with tripods that don't have built-in leveling mechanisms. Its three adjustment dials enable the operator to make fine, finger tip adjustments up to +/- 5 degrees to ensure the camera is perfectly level. The dials also have locking rings to ensure stability once the right position is reached. A spirit level is built in for reference. The base has a 3/8" female tripod fitting and a 3/8" male head fitting.