The closing of the pump can be in a lock-up position like the P2000.
Or a lock-down one like the SD20 which enables the user to turn the head to the left or right in the lock-up position or unscrew the head from the closure in the lock-down position.
The advantages of a lock-up pump is that you can close the pump after using it. The disadvantage is that the pumps are more expensive and have a limited top load.
The lock-up pump P2000 is produced with a pure path engine which ensures that the user has metal free dispensing. The spring mechanism is also not in contact with the product, thus eliminating any risk of contamination and oxidation by having contact with the contents.