The four classes of extremes -- high heat, heavy precipitation and floods, duration and intensity of droughts and extremes related to higher sea levels -- have changed in the last 50 years, Field said.
They are certified to MIL-STD 810G for extremes in temperature, vibration, shock and four-foot drops and have an IP65 rating for ingress protection, which means they are fully protected against dust and can withstand low pressure jets of water from all directions.