The short 6 feet leader is designed to give maximum turnover for big flies. It can be used with fast sinking shooting and Skagit heads to take your fly really deep. This is also a good base to build your own pike leader by adding a piece of wire at the tip
9 feet version is at its best with single hand fishing for bigger fish. It is also good choice for slower sinking shooting heads.
The 12 and 15 feet leaders are great for all around salmon and steelhead fishing.