as others have posted, they don't know what they're talking about. here's what the Seal Check system actually does.
Verify housing integrity before entering the water
Seal Check II represents the next generation in Gates legendary reliability by allowing confirmation of housing seals before entering the water – virtually eliminating water intrusion as a source of downtime and unexpected expense.
History reveals the top three flood causes are damaged o-rings, rushed setup and unfamiliarity with equipment. With Seal Check II there is peace of mind ahead of time. A precise digital readout provides a clear indication of housing integrity -- giving you the go / no go decision -- and aids with troubleshooting should the need arise. The electric pump quickly pulls a measurable vacuum, all contained in a small Pelican case. Seal Check II is also available with an optional self-install kit for non-Gates housings, too.