The Huben K1 barrel was optimized to work with the Huben K1's design. This is a relevant feature as the K1 shoots straight from the magazine. Good, generic barrels might not work that well in these cases; this barrel, specifically meant for the K1, guarantees excellent performance.

This barrel was designed to shoot well both pellets and slugs. Unchoked as it is, it works very well with slugs, and, in the meantime, a slow twist rate and 12 grooves mean that, despite the high velocities that the K1 generates, pellets don't overspin.
This barrel comes with the magazine installed.