I'm selling this because I'm currently using a different one. The size feels like a size M. I'm currently using a size M, so it felt the same. This is a magnetic necklace I bought at a general goods store. It's a no-brand item, so I remember the mt (millitesla) was also low. I think it was around 100mt. For reference, it cost about 8000 yen when I bought it. *mt = unit of magnetic force. It reacts with the iron in the blood in your neck to promote blood circulation and relieve stiffness. Please note that individual results may vary. If you have any other questions, feel free to comment. #MagneticNecklace