The Medium Rocker butt plug offers a slightly bigger length and thickness to the small version.The tapered shaft assists insertion aswell as creating an auto thrust effect during use with your stimulator. Subtle textured ridges enhance sensation while the unique rocker base helps guide you to an anal orgasm. The base features concealed connection for your stimulator, allowing you to rock and grind against it during play for the ultimate hands free experience.ElectraStim stimulators sold separately.