This is a portable telephone cord made by SONY. I bought it over 20 years ago and used to carry it around when I was communicating using a modem on my laptop. I used it when I needed to connect to a phone line while on the go, but I only remember using it a few times. I kept it in my bag for a long time, so there are some minor scratches on the outside, but I've cleaned it thoroughly, so I think it's in good condition. I tested its operation by connecting it to a landline phone before listing it, and it works perfectly, with no disconnections or anything. You can use it with confidence. The following is from the manufacturer's page: https://www.sony.jp/products/Consumer/Peripheral/ModemAccessory/acc.html?srsltid=AfmBOop2Vx19IwnXs6Pf-RjfCPYSZiks80Bo16nqQkXGdPrHfG0vPsII#7 【Specifications】 ■ Size: Approximately 150 x 16 x 16mm (excluding protrusions) ■ Cord length: Approximately 0.8m (between modular plugs when extended) ■ Weight: Approximately 20g ■ Features 　Convenient to carry because it's pen-shaped. 　Easy data communication from mobile information devices while on the go. 　"It also comes with a relay plug, so it can be used for various purposes." ■ Suggested retail price: 2,500 yen (excluding tax)