The wireless 4-9 provides freedom of movement and convenience. It operates wirelessly, comes with 2 independently controlled wireless receivers, and offers 9 different modes of sensation. Up to 4 receivers can be used with the device (sold separately) allowing for the use of up to 8 electrodes at once. This second-generation wireless device is ideal for giving yourself therapy on the go without the hassle of wires, and is also optimum for use while engaging in your workout routine. The Wireless 4-9 package includes: