The 338 is fitted between tripod and head and is used in combination with tripods that don't have built-in levelling 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.