1. Left-hand pinky key
2. Left-hand thumb key
3. Right-hand pinky key
4. Right-hand middle key (AKA palm key)
Remember all keys must be simultaneously played (all the way down) so there are no air leaks. Depending on whether your saxophone is pitched in high A or low A you may or may not also include your right-hand index finger for this fingering. Some low As even require the use of an added Bb extension.