Back Side Connectors Additional Information 3″ #40-5022 4″ / R-1 #40-5023 4” / thruflow #40-5108 5″ #40-5024 Starting from $26.50* *Taxes not included 40-5022 / Connector side 3" 40-5023 / Connector side 4" / R-1 40-5108 / Connector side 4" / Thruflow 40-5024 / Connector side 5" Find a retailer Need more information? Find a retailer Need more information?