Wireless (connectorless) headsets or headphones usually use the Bluetooth protocol. HAA can work with both wired and wireless headsets and headphones. Plantronics manufactures mobile headsets, including a line of Bluetooth headsets for mobile phones. Newer models allow the connection to wireless headsets via Bluetooth. There are two types of Bluetooth headsets. Single-earpiece headsets are known as monaural headsets. Mobile (cellular) phone headsets are often referred to as handsfree. The company is mainly known for its line of wireless Bluetooth sports headsets. Shure also manufactured specialized headsets and the MC-1 oxygen mask microphone. These are used both for handsfree headsets (esp. Noise-cancelling aviation headsets are now commonly available. Version 1.60 also adds support for Pulse Elite wireless headsets. Not all telephone headsets are compatible with all telephone models. Dynamic binaural audio was common to most headsets released that year. Virtual reality headsets and viewers have also been designed for smartphones.