Product description
The MyoWare® 2.0 Muscle Sensor is designed to be wearable, allowing you to attach biomedical sensor pads directly to the board itself. However, there still may be cases where you want to mount the sensor pads away from the board; this is where the MyoWare 2.0 Cable Shield comes in. The shield includes a 3.5mm TRS jack where you can attach a traditional three electrode sensor cable, allowing you to test and use the muscle sensor without actually attaching the board to your person.
More information is available on the website of Sparkfun.