I have them on receiver tubes.

Hello John, I figured somebody would pick-up on that one and wonder what the heck that was all about. Of course when I took the pictures I wasn't focused on what was in the peripherals. To answer your first question, the inserts are 6" long, yes you are also right, it would be better if they had keeper pins or some other sort of retention set-up, although to date I haven't lost one yet. As to the sign, I could make up some sort of wild story along the lines of your comment, but I'll try to be honest and include the real story. One of the local mills has land holdings to go along with their paper-making operation. They approached us about a project to make some signs to put up in the areas of their logging operations, so that's the example piece. They are providing the materials and any other necessary items. There you have it John. Best regards, Allan