51/48/41MM Exhaust (Step) Adjuster Pipe . These little friends help you to fit a muffler on a modern exhaust. Available in multiple sizes and in stainless.

This one:  51/48/41MM
This is the outer diameter
The material has a thickness of 1.5MM

So, a 51/48/41MM pipe has a 48/45/38MM inner diameter.

Price PER 1 piece