If insertion is difficult, please check the following points. ・Make sure you have removed the sticker from the top of the product. If the sticker is still attached, air will not escape, making insertion difficult. ・If you experience pain during insertion, apply a little lotion to your erection to make insertion smoother. If you still experience pain, please try a CUP which is one level of stimulation lower. ・If you are unable to insert into the device, your erection may not be hard enough. Try a CUP with one Level lower stimulation (the elastomer should be softer and easier to insert into).