This Supply Giant no-hub coupling, with a diameter of 3 inch , is the extra heavy. The main difference with a standard no-hub coupling is that it has more clamp rings for the same size fitting. Furthermore, this specific part has a coloured shield for signalling purposes. UPC , UL and FM approved the design for meeting all applicable standards. ***CALIFORNIA PROPOSITION 65 WARNING: This product can expose you to chemicals including Phthalates content which are known to the State of California to cause cancer, and birth defects or other reproductive harm. ⚠ California Proposition 65 Warning: This product is known to the state of California to cause cancer, or other reproductive harm. For more information, go to www.p65warnings.ca.gov. ⚠ California Proposition 65 Warning: This product is known to the state of California to cause cancer, or other reproductive harm. For more information, go to www.p65warnings.ca.gov.