Post thickness → 0.7mm Length → Approximately 0.9mm Initial thickness → Approximately 0.4mm Initial 【Y】 Approximately 5mm tall and wide The post and everything else are K18, but the K18 stamp is only on the catch. In the past, there were also items without stamps on the post. You can only judge by the photos and the construction. If you are concerned, please refrain from purchasing. K18 catches tend to loosen and are easily lost, so recently people have been switching to silicone types. (It's best to store the catches carefully) Weight measurements are approximate. Errors may occur depending on the measuring instrument. We do not accept returns or exchanges to prevent substitution, so please consider this before purchasing. Price negotiations are not possible. There are no other letters.