Thank you for viewing. It's 18mm-15mm. The material is not listed, but it appears to be sharkskin. The buckle side is slightly larger, so please crush it to use. This is a long-term storage item. There are dullness and stains due to long-term storage. If you have any questions about the product, please feel free to ask. Also, I don't know if I can meet your expectations, but feel free to negotiate the price (excluding significant discounts). Please include your desired price when negotiating. Please refrain from comments if you are just browsing or not considering a purchase. The following concerns the transaction: ・First, please also see my profile. ・I will not respond to setting a desired price. This is because many people do not purchase. ・I will not respond to standard discount comments. Please state your desired price. ・If, after price negotiation, both parties agree but then the buyer haggles again, I will immediately block them. ・Due to a history of drop shipping, if you do not reply within a certain time after a price negotiation, I will delete my reply comment. ・This is a personally owned storage item. Regardless of whether it is new, unused, or in good condition, there may be minor scratches or oversights in addition to the content described. ・Please refrain from purchasing if you are looking for the same level of service as a store, are nervous, or do not understand used items. ・Please ask any questions before purchasing. Please make a purchase after you are satisfied. ・To prevent substitution, cancellations, returns, and exchanges are not accepted after purchase, so please purchase with caution. ・To prevent trouble, I may delete the comments of new users or those with many "bad" ratings, or even if there are few ratings, depending on the content of the ratings, so please be aware of this. ・Packing for shipping will mainly be recycled cardboard, etc.