Yurbuds Ironman Series Earbuds feature ultrasoft, medical-grade silicone enhancers that fit the contours of your ears, providing exceptionalfort for long periods of time. Patented Twist-Lock Technology guarantees that they will stay in your ears during rigorous exercise, even when you sweat or train in the rain. The ergonomic design provides rich sound and deep base, but not at the expense of safety as you will be able to hear traffic and talk to your training partner. 3.5mm gold-plated stereo mini plug works with most digital music players. Sz: One size fits most.