Nordic Components Shotgun Tube Extension Assembly (Nut Sold Separately) - 12 ga.

These shotgun tubes are precisely machined from strong lightweight aircraft grade 6061 aluminum tubing. You can add anywhere from +1 to +9 rounds. Barrel nuts are designed to match OEM styling. Kit includes extension, spring, and end cap. Tube has an OD of 1.06"

+9 – Adds 22.5 to 22.9 inches
+8 – Adds 19.8 to 20.2 inches
+7 – Adds 17.1 to 17.3 inches
+6 – Adds 14 to 14.4 inches
+5 – Adds 11.6 to 12 inches
+4 – Adds 10.1 to 10.5 inches
+3 – Adds 8.3 to 8.7 inches
+2 – Adds 5.7 to 6.2 inches
+1 – Adds 3.1 to 3.5 inches

Barrel nuts are Sold Separately

https://www.makereadyproshop.com/nordic-components-shotgun-mag-tube-barrel-nut/