Run the post through the hole first to get a custom fitting, them put the earring on. These are lots of 50 large clear stoppers for the back of earrings. They prevent french hooks and others from falling off. 3.8mm long, 5mm diameter. Translucent silicon rubber flexible stoppers. Ribbed cylinder shape, easier to use. Safety backs earring wire stoppers.Help avoid earring loss translucent earring safety backs medium size lot Of 50; provides a tight fit; use care when slipping it on narrow wire.