If you want only 20- or 28-gauge or can't part with your gun for that long, consider Briley Companion Tubes. These drop-in sets are pre-made for popular shotgun models and are priced comparably to fitted sets. They can even be used in most other guns of the same make and barrel length. The downside is that they aren't hand-fitted. A plastic "button" friction-fits them in place, and the hold usually isn't as strong as with a fitted set.