ALL COUPLERS COME IN 3" LENGTH AND ARE MADE OF HIGH TEMP 4-PLY SILICONE. 
 
4"  -   550,650,750 AFTERMARKET SYSTEMS, B PIPE CHAMBER TO MANIFOLD
 
4.5" 
 
4.75"  -  X2 & 650 & 750 Aftermarket exhaust systems, Westcoast, Jetsport, Butch's
 
ABOVE IS FOR REFERENCE ONLY AND ALWAYS MEASURE THE COUPLER OR EXHAUST YOU HAVE BEFORE ORDERING. 
 
ALL SIZES ARE INSIDE DIAMETER