Complex sentence: Both stars are small red dwarfs, with each having just over half the Sun's radius, and around a third of a solar mass. Both display variability common to flare stars, and their active surfaces are sources of X-ray emission.
Split into simpler sentences: Both stars are small red dwarfs, with each having around a third the Sun's mass and radius. They each display the type of variability common to flare stars, and their active surfaces are sources of X-ray emission.