You can judge by the second letter of the slider part number.
"A" = automatic lock (When you release the hand from the Zipper’s Pull Tab automatically is locked, the lock is disengaged by pulling the Zipper’s Pull Tab)
"F" = non-locking (slider that does not lock the pull tab at any position on the fuselage)
"N" = Notch lock (The torso has a notch on the shoulder and locks when the chain is opened so that it touches the shoulder)
"W" = reversible (there are Zipper’s Pull Tab on the front and back, which can be opened from both)
"U" = reversible (an automatic slider that allows one puller to move along the rotating rail and can be opened and closed from both the front and back.)