The 
FC5644 Rubber Coupling Flexible Connector - 4" x 4" is a type of flexible pipe coupling used for joining non-pressure drain, waste, and vent piping systems. It is manufactured by various companies, but the most prominent equivalent/alternative product is the Fernco 1056-44. 
Key Features and Specifications
Size: 4 inches x 4 inches (nominal).
Material: Made of elastomeric polyvinyl chloride (PVC) with corrosion-resistant 300 series stainless steel clamps.
Pipe Compatibility: Designed to connect a variety of pipe materials including plastic (PVC, ABS), cast iron, copper, steel, or lead pipes.
Applications: Primarily used for sewer, drain, waste, and vent piping applications, both indoors and outdoors, and is rated for underground use.
Pressure Rating: Maximum test pressure of 4.3 PSI.
Temperature Range: Suitable for temperatures from -30°F to 140°F (-30ºC to 60ºC).
Resistance: The coupling is leak-proof, root-proof, and resistant to chemicals, UV rays, fungus growth, and sewer gases.
Installation: Easy to install with a screwdriver or torque wrench; no special tools, primer, or glue needed.
Certifications: Conforms to industry standards such as ASTM C1173, ASTM D5926, and CSA B602, and is UPC approved.