Remington OEM Two Shot extension kit, 20ga LW
Factory New Remington 20ga two shot extension kit. If your 20ga 870 serial number begins with the letters RS or ends with the Letter then you have a LW 20ga and this fits your gun. Same as the Remington 12ga two shot extension but sized down for the 20ga. You get the tube, Spring, magazine tube coupling, follower, extension bracket with QD stud and screw.
Find the 12ga in this same category and you will find two videos. The first one shows you how to adapt your gun for this tube extension and the second ones shows how to install it.