These are the first earrings of this type I’ve ever come across. They are 9ct gold with impressed mark to the back of the metal loop. They are for un-pierced ears though people with piercings can still wear them. The hollow ball fronts are attached by a gold metal loop which fits to the back of the ear lobe and pressure holds it in place. I have never worn these, they are my sisters, she said they stayed on fine. Andraslide earrings were made in the 1960s-1970s and the wearer literally slid the earring into place on the lobe. My sister said that for her, they were comfortable to wear and very easy to fit when you get the hang of it. They are pretty quirky and cool. Happy to answer any questions if I can. Thanks for looking.