Fernco 4-in. Ideal Flexible Neoprene Coupling Fittings for Cast Iron Pipe - Quick and Simple ConnectionFernco's no hub couplings are used by professionals nationwide. These high quality no hub couplings have a unique beaded neoprene gasket that grips with superior holding and sealing power. The wide bands and one piece screw housings are mechanically interlocked for strength. The wide clamp band provides enhanced sealing force. Fernco's no hub couplings have earned a reputation for consistent, superior performance, and you can have full confidence in