Sized specifically for the 20 gauge's 0.615" bore - not a 12 gauge snake squeezed down, but a purpose-built pull-through cleaner that fills the bore correctly. The woven floss section makes full contact with the barrel walls, and the built-in bronze brush scrubs through plastic wad residue and carbon that accumulate after every round. Drop the brass weight through the breech, pull the cord, and the bore cleaning is done in one pass.
The 20 gauge is the choice of upland hunters, youth shooters, and anyone who wants lighter recoil without giving up effectiveness. These guns often see heavy use during bird season - multiple hunts per week, sometimes back-to-back days. A bore snake in the vest pocket means the bore gets cleaned in the truck before the drive home instead of waiting until the weekend for a full rod-and-brush session. That matters because shotgun fouling - especially plastic wad buildup - hardens over time and becomes progressively harder to remove.
Wash the bore snake when the floss darkens with fouling. Hand wash with warm soapy water or gun cleaning solvent, air dry completely, and store in a clean bag. One pull-through bore snake handles the everyday maintenance that keeps your 20 gauge shooting patterns tight. Save the deep cleaning for the end of the season.