The Hammerhead Heart Rate Monitor is designed to work with the Hammerhead Karoo Computer, but is compatible with any smart devices that share 2x Bluetooth channels and ANT+ connectivity. The Hammerhead Heart Rate Monitor is washable, includes all-fabric electrodes that allow for great connectivity and durability and is designed for overall fit and comfort. Features: Get more out of your Karoo 2 with real-time heart rate data Adjustable, washable, elastic strap 30m (90f) Waterproof R-R Intervals Specifications: Strap length: 28"-48" Electrode material: Fabric with woven silver Connectivity: 2x Bluetooth channels and ANT+ Battery life: 900+ hours Battery type: CR2032 3 volts (included) Color: Black Weight: 15g (pod) 28g (strap)