LED ring used is this one https://www.aliexpress.com/item/4000877848238.html?spm=a2g0o.order_list.order_list_main.52.49db1802CrgEs4

But any 48x1,25 mm should work. This should be the “standard” size so if you have 16 LED ring, chances are it is 48 mm in diameter. 

The guides/holding part is 150° wide so the ring is pushed in and holds.