Thank you for viewing. This is a sensor that detects a baby's breathing. It's the type that attaches to the baby's stomach. I purchased this when my first child was born in 2021 because I was worried about Sudden Infant Death Syndrome (SIDS). I think I wouldn't have been able to sleep without it, especially during the period when the baby could roll over but couldn't roll back. Even after the baby could roll back, I was still worried about SIDS, so I used it until the baby was 1 year old. I planned to use it for my second child this year, but for some reason, I wasn't very worried, so I didn't use it. If you are considering the type that is placed under the baby, why not give this a try? Please purchase only if you understand that this is a used item. ⚠️ There are no noticeable scratches on the main unit, but the instruction manual is creased. ⚠️ Please forgive any minor scratches, as this is a used item. ⚠️ There is no case or box. ※ Operation has been confirmed. ※ For safety reasons, batteries are not included. ⚠️ As this is a used item and inspected by a non-professional, please be sure to check the condition after receiving it. After the receipt evaluation, it will be difficult to respond due to the Mercari system, so if there is a malfunction, please be sure to contact me before the receipt evaluation. I will do my best to respond sincerely.