End Goal
No End-Date: These tests will run indefinitely until you “Select a Winner” or “Pause/deactivate” the test.
Visitor Count: You specify the amount of visitors each variant will need to achieve (at a minimum) to end the test.
Custom Parameters: Define custom test parameters to create a custom sample size/visitor goal that each test variant must achieve before the test is considered complete (and variant changes no longer occur):

This feature is best suited for store owners who have very clear objectives with their A/B Testing needs and want to ensure their tests are ran in a statistically significant manner. See this article to learn more about statistically significant A/B Testing:
https://www.invespcro.com/blog/how-to-analyze-a-b-test-results/