These MSD Weathertight sealed connectors are molded from a special nylon material to withstand temperatures from -40 to 257 degrees F and are indexed to prevent mismatching. Positive locks let you know when the connectors are joined correctly with an audible "click", while each terminal has its own tower so there's no chance of shorting. And lastly, silicon seals prevent water, chemicals, and dirt from entering, for a truly reliable, maintenance-free connection.