The transmission range of Bluetooth LE and ANT+ heart rate sensors is usually 10 to 40 meters (32.8 to 131.2 ft) indoor and it can reach up to 100 meters (328.1 ft) in the open air. Since the transmission range of sensors can be affected by many variables it is not possible to state a unique value. Transmission range can be increased with a line-of-sight positioning between the sensor and receiver. The radio signal might be attenuated and the range considerably reduced by obstacles like TV screens, mirrors, walls, columns, doors, etc. However, the radio signal bounces from wall to wall improving the transmission range within a room in case of no direct line-of-sight positioning between sensor and receiver. Signals from other electrical devices and high air humidity may also have a negative impact on the transmission range. Please also consider that the human body might create considerable Bluetooth and ANT+ signal attenuation when facing opposite of the receiver.