✔️ Athlete Tested Reliability: Refined & tested by endurance athletes for class leading Heart Rate Monitor Chest Strap connectivity with dual-band Bluetooth 4.0 & ANT+ protocol. Powr Labs Chest Heart Rate Monitors are absurdly reliable. , ✔️ Unrivaled Warranty: Unlimited heart rate monitor battery replacements & no questions asked warranty for 12 months. , ✔️ Broad Compatibility: Works real-time with both smartphones & GPS devices compatible with Bluetooth and ANT+. Fits all athletes with adjustable strap from 26" to 38". , ✔️ Pro Durability: With full IPX67 water & sweat proof design, the Powr Labs Chest Heart Rate Monitor has been battle tested by professional cyclists, runners, triathletes & fitness competitors. *note: While waterproof rated for full submersion, we do NOT recommend swimming in this heart rate monitor. , ✔️ Pairing Instructions: To pair, chest strap must be worn across chest. Apps we recommend: Endomondo, Elite HRV, iCardio, Heart Graph for all types of exercise; Map My Ride, Wahoo, Garmin, Polar Beat, Zwift, Peloton for cycling; Map My Run for running. The device will not work with Google Fit and requires an iWatch to connect with Apple Health. Reach out if you ever have compatibility questions!