This is the Blue Silicone Pipe Coupler for the T-Maxx 2.5            

This goes between the tuned pipe and the header                                                                                                  FEATURES: Blue silicone construction                                                      For use with pipes #5152 and #4452                                                                                                                    INCLUDES: One pipe coupler                                                                                                                                      REQUIRES: Installing on the vehicle with wire ties (can use ASCC3720)                                                                                           SPECS:    Length:   21mm                                                                  Diameter: 11.5mm ID & 17.5mm OD (small end)                                               15.8mm ID & 21.5mm OD (large end)