Adidas Techfit compression top. This top is for training and exercise. It has a spot on the chest to attach a heart rate monitor, and I used to attach a Garmin heart rate monitor. I usually wear a size M, but there's no tag. I think I bought a size M, but it feels like a size S due to the compression. The compression is tight, and I've only used it a few times. Size: M (Fits like a Japanese size S) Type: T-shirt Sleeve: Short sleeve Gender: Unisex Features: Compression