The Weathertight connectors are molded from a special nylon material to withstand temperatures from -40° to +257°F and are indexed to prevent mismatching. If you need electrical connectors that are unaffected by water, chemicals, vibration, temperature or dirt, and that will not come apart accidently, then you need MSD Weathertight Connectors. Positive locks let you know when the connectors are completely joined by producing an audible CLICK. No click means no connection.For maximum electrical isolation, each terminal has its own tower so there is no chance of shorting between the wires. Each terminal tower utilizes self-lubricating silicone seals for protection against water, dust, oil, and other engine compartment fluids.