A two-in-one blend of stimulation! The Bitter Side firmly tightens while the Sweet Side gently clings to your shaft. Normal use is one side at a time; however, simultaneous use of both will provide a brand new feeling of two contrasting sensations! To create a strong internal vacuum, simply remove the sticker at the top of the cup before use and cover with your finger while using. Cup features the smooth pad insertion mechanism! This mechanism not only offers extra adherence, air-tightness and less lubricant leakage, but will automatically apply lubricant to your shaft as you insert!