THIS IS THE HEAT EXCHANGER TUBE BUNDLE ASSEMBLY FOR THE 403A, 403B, 405A, AND 405B HEATERS THIS IS A STANDARD COPPER, 9 TUBE BUNDLE LENGTH IS 22" FROM OUTSIDE OF END PLATE TO OUTSIDE OF END PLATE INCLUDES: (1) TUBE BUNDLE (18) ROUND HEADER GASKETS (1) STAINLESS STEEL LINER FOR 6 STUDS (1) STAINLESS STEEL LINER FOR 8 STUDS (6) CARRIAGE BOLTS 2-1/4" LONG (OR STUDS) (2) CARRIAGE BOLTS 2-3/4" LONG (OR STUDS) (5) CARRIAGE BOLTS 3" LONG (OR STUDS) (1) CARRIAGE BOLTS 3-1/2" LONG (OR STUD) (14) FLANGE NUTS (8) HEAT EXCHANGER TOP BAFFLES (1) SET OF INSTRUCTIONS NOT ALL OF THESE ITEMS ARE SOLD SEPERATELY THIS IS THE LIST OF AVAILABLE PARTS 6230-17 800014B HEADER GASKETS (SET OF 9) 6230-16 003103F STUD BOLT KIT THIS INCLUDES ALL OF THE CARRIAGE BOLTS AND ALL OF THE FLANGE NUTS 6230-15C 001302F HEAT EXCHANGER TOP BAFFLES (SET OF 8)