Awhile back, I think it was Glem.Chally mentioned trim rings foe SK 19 gauges. They were printed by SMWE Engineering out of Briton, [email protected]. I have a few fixed magazine guns and repeatedly scrap the end while loading. I place moderator on the end of my boot to not scratch the end of the moderator. It inevitably slips off and scratches the end cap. Something was need to prevent this. I contacted Stuart to find out if he could print a protective boot, he responded positively. A couple of emails back and forth they were designed. They are made of a flexible plastic that snugly fits the end of your moderator, around 25mm long. I gave Stuart the diameter of the moderator to be capped and he printed them up. I haven't given them a field trial yet but seem to fit smugly enough that they won't fall off. I thought the price was reasonable at 6.00 pounds each, the wonders of modern technology.