First, it is very important that you use the correct size enhancers (rubber tips). This headphone features the TwistLock technology that is uniquely designed to fit in the bowl of the ear (vs. inner ear). They may look bigger than traditional earbuds, but this design provides the most secure fit to ensure they never fall-out in the most active workouts. To properly put them on, first make sure you have the Right and Left earbud in the correct ear. The number to indicate the enhancer size is featured on the inside of the enhancer next to the large L or R (left ear, right ear). Next, gently insert the enhancer into your ear with a forward motion towards the jaw, which should twist and lock the enhancer into place. These headphones come with 5 sizes of fit enhancers (4, 5, 6, 7 & 8) and 3 sizes of ear tips (small, medium & large). The fit enhancers sit in the bowl of your ear and are essential for a secure fit, while the ear tips are inserted in the inside of the ear canal and provide sound occlusion. The size 7 fit enhancer and large ear tip comes pre-installed on the headphone. If you experience discomfort wearing the size 7, try the next size down. If you try a smaller size and the headphones fall out easily or the enhancer does not extend fully to the back of the bowl of the ear, you should try a bigger size.