Invector-DS is Browning's newest evolution of their legendary Invector choke system.

For use only in compatible shotguns, “DS” stands for double-seal, Browning's proprietary differential-banded brass seal. It compresses against the barrel wall to keep the choke tube threads clean and makes installation and removal easier than any other muzzle thread system.

The extra length choke tubes combine muzzle-end threads and thin-wall construction for a longer, more gradually tapered choke tube that produces extremely consistent, dense shot patterns. The more gradual taper of Invector-DS choke tubes reduces shot deformation for fewer flyers and gaps in the pattern and allows higher shot velocities for hard-hitting performance.

Invector-DS  is standard on A5 and Citori 725.