Arrow Mufflers for the Husqvarna 701 Enduro/Supermoto require a 'link' pipe to adapt to either the stock or Arrow header. The reason for this is because they use the same front caps on many different models of their mufflers and 'adapt' them with a link pipe to the stock or Arrow header. If you do not already have an Arrow muffler, see one of the links below and add the Link Pipe as an option on that page.
See these links for available Husqvarna 701 Enduro/Supermoto Mufflers:
Warranty fulfilled by Arrow Exhaust.
Posted by cris on 2nd Jul 2018
This is needed to install the Arrow can on the stock or Arrow header. It does its job, and is easy to install. Note though that the stock graphite washer (which needs to be reused) is very hard to get off the stock can without damaging it, but you can get a replacement one from Husky or KTM for a few bucks that just slides on and makes install a snap. I'd just get a new one and not mess with the old one.