What is the purpose of the latch on the new L&L Spring Hinge?

What is the purpose of the latch on the new L&L Spring Hinge?

This latch should be closed/used during firing of the kiln. We provide it because the lid is light enough with the spring hinge so that it could rise slightly during firing.

If you prefer the lid to be heavier you can adjust the spring tension using the alternate slot in the back, or remove one of the springs or change the way the the spring is installed.