The base inner diameter is 16. Only size adjustments down to 13-16 are possible. For sizes larger than 16, please confirm if it's possible before purchasing m(_ _)m I'm posting videos on Instagram ▶︎ ichigohime__ Please read the profile before purchasing. ♡ I fell in love with the tiger eye bear charm, it's super cute, but there's only one! First come, first served (lol) ※ The effects of tiger eye are said to enhance insight and decisiveness, improve financial and career luck, give confidence and action, dispel negative emotions, and guide the owner towards achieving their goals. It is especially believed to be a strong ally in achieving business success, increasing wealth, and overcoming difficult situations. I do not accommodate metal allergies, but if I have the stone in stock, I may be able to remake it without the metal parts, so please check before purchasing ( ´._.`) As it is completely handmade, please understand and purchase. ※ Please check the images carefully, make your own judgment, and ask any questions or concerns before purchasing. Returns, refunds, and exchanges are not accepted after arrival. I am a handmade seller! Please understand. If you are looking for perfection, please purchase from a shop. (※) The price includes shipping, packaging, and handling fees. I reject bulk purchases with a discount on the shipping fee because it doesn't make sense. (※) If you want a discount or a discount for bulk purchases, please leave a comment m(_ _)m If there is no comment, it will be rejected. Please also read the profile (♡ᴗ͈ˬᴗ͈) I do not accept custom orders, only size adjustments.