The H100 series telephones are fully contained within a corrosion-resistant cast aluminum weatherproof case and cold rolled steel faceplate with epoxy powder coated providing complete protection against dust and moisture ingress, resulting in a highly reliable product with a long MTBF. Extremely easy to install. The cable entrance is on the back of the phone to prevent from artificial damage resistant. 
The H100 series Weatherproof Telephones are designed for use by the highway, railways, power stations, the armed services and heavy industry which require very reliable telephony under adverse conditions.