C13 Secure Sleeve
For whatever odd reason, manufacturers of the C13 plugs and receptacles do not get together on a standard to ensure a snug fit between them. The heavy power cords I use tend to move and fall out with only a slight touch. The sleeves are a big help to tighten the connection between plug and receptacle. The sleeves are a VERY tight fit on the plug, not easy to slide on, and are about 1/8 inch too long. Despite that, they are far better than plumber's tape around the plug, and worth the small investment.