The Pelican cases we use have an IP67 rating. In the International Protection Marking system (IEC Standard 60529), the first number (6) assures there is no ingress of dust and complete protection against contact (dust tight) with a duration of up to 8 hours based on air flow. The second number (7) assures there is no Ingress of water in harmful quantity when the enclosure is immersed in water under defined conditions of pressure and time (up to 1 m of submersion).
When the cases are open, we include several secondary systems to keep the weather out such as unique snap lids on all connectors, and any cables that go outside the top panel have protective jackets.
There is an Automatic Pressure Equalization Valve that balances interior pressure and keeps water out. The lids have an O-ring seal assuring a tight seal when closed. The double throw latches keep the lids secure, and there are stainless steel padlock protectors.
The custom-designed air vents have removable filters for both ingress and outgress. There are 14 fans inside the larger units to keep everything running cool, the main fan is variable speed controlled by temperature sensors.