AT Series™ Connectors Amphenol Sine Systems AT Series™ Connectors are a high-performance, IP68/69K rated (mated), thermoplastic, cost-effective solution with superior environmental seals and seal retention capabilities. The connector design incorporates an integral latching system that ensures a definitive electrical and mechanical connection. All of AT Series connectors offer a wide range of end caps and strain relief options and have been developed to be compatible with all other existing standard products industry-wide.