When I spoke with a T/C rep after getting my 20" .45-70 Katahdin Encore barrel, I was told they are named after Mount Katahdin in Maine. They have released them as 18" and 20" barrels. The 18" barrels came out first and were chambered in .45-70, .444 Marlin and .450 Marlin. The 20" barrels are currently available chambered in .45-70, .500 S&W, .460 S&W and 209X50.