COMPATIBLE WITH HEART RATE SENSORLIVLOV V11 armband heart rate monitor soft strap width is 22 mm, compatible with most heart rate sensors (ANT+, Bluetooth). Compatible for LIVLOV V9, Polar Verity Sense, Wahoo, Powr Labs, VorTec, smartLAB, Echelon, Fitcent, XOSS heart rate monitor armband. Not compatible Scosche, orange theory, OTBeat heart rate monitor and other hr sensors wider than 22mm. ADJUSTABLE SIZINGThe package contains two different lengths of heart rate monitor armbands for men and women. Replacement armband length (L * W * H): Black-400 * 22 * 3.2mm, orange-355 * 22 * 3.2mm. Please check the desired size before purchasing. COMFORTABLE AND BREATHABLE ARMBANDThe arm band is made of silicone and Leica material. Wear comfort and soft, easy to clean, durable. Ensures your device stays securely attached to your arm during climbing, biking, running, and intense workouts. WEARINGWear armband on the upper portion of the forearm. Sensor should be on the inside or top of forearm. It should be worn snug enough not to move on your arm, but not so tight that it restricts arm circulation. SERVICETest without risk. If the replacement soft belt should not fit your heart rate sensor, please contact us on the order page and LIVLOV will reply to you within 24 hours. Note: Only arm belt, heart rate monitor is not included.