The full answer
The essential HMS requirement is that the animal must still be alive when the valid Zabiha slaughter occurs.
A procedure that causes the animal's death before Zabiha would make the meat impermissible.
Rather than asking consumers to determine the technical details of industrial stunning equipment themselves, HMS verifies approved slaughterhouses and their processes.
Answers in the Halal Knowledge Center reflect the standards followed by Halal Monitoring Services (HMS), which operates as part of the Shariah Board of America. HMS certifies only what it checks.