Exhaust pipe to muffler reducer / adapter. Use this to put different size mufflers on different size head pipes. Comes with 3 reducers and sold as a set of 2. Slide them apart to change the size needed.

Adapts or Reduces 1-3/4" inlet to suit 1-5/8" pipe
Adapts or Reduces 1-3/4" inlet to suit 1-1/2" pipe
Adapts or Reduces 1-3/4" inlet to suit 1-3/8" pipe
Adapts or Reduces 1-5/8" inlet to suit 1-1/2" pipe
Adapts or Reduces 1-5/8" inlet to suit 1-3/8" pipe
Adapts or Reduces 1-1/2" inlet to suit 1-3/8" pipe
This is the same reducer that comes with Emgo Mufflers (80-47310):
Cafe Muffler - 80-84033
Universal Reverse Cone Shorty Muffler - 80-84030 / 80-84030B
Universal 26" Reverse Cone Cafe Muffler - 80-84034