See that's the weird thing, the link to a 'cavity plug' in the article (about halfway down) takes you to this page: https://www.fischer-international.com/en/pr

See that's the weird thing, the link to a 'cavity plug' in the article (about halfway down) takes you to this page: https://www.fischer-international.com/en/products/cavity-fixings/board-fixing/metal-cavity-fixing-hm/519772-hm-5-x-37-s https://www.fischer-international.com/en/products/cavity-fix... That looks a lot like what I'd call a molly bolt I just googled a cavity plug and I'm not sure I'd use it in this application