Review on Black Plastic Tubing Package Caplugs by Ryan Turner

These are not panel knock out plugs but plugs to be used in tubing as in furniture. They didn't work in my application to plug holes in a circuit board. My main fault was not reading the full description, although you would think the search algorithm would exclude them based on a "panel knockouts" search. With that in mind, they seem to work well for plugging pipe/hose ends.