Check Valve and Adapter The FATSAC Check Valve and Adapter is a two part fitting that replaces the FATSAC Quick Twist/Sac Thread Adapter that comes with ballast bags. The FATSAC Check Valve and Adapter is an optional upgrade for FATSAC ballast bags that replaces the standard Quick Twist Adapter.  Just as easy to connect and disconnect as the standard fitting, the W744 Check Valve adapter also features an integrated check to prevent water from exiting the bag when disconnecting and connecting the pump for filling or draining. Features: * Air Inflation Valve - simply use a standard air pump to inflate * Includes all O-rings needed, and by-pass adapter fitting for emptying water * Manual 1 way check valve when manually filling bags with Supa Pump  *Sold as in individual Warning [https://productimageserver.com/prop65/6pt.png]WARNING: This product can expose you to chemicals including Diisononyl Phthalate (DINP) which is known to the State of California to cause cancer. For more information go to P65Warnings.ca.gov [http://P65Warnings.ca.gov].