There are 5 sizes of fit enhancers that come with the UA Sport Wireless: (4,5,6,7 & 8). Size 7 on the earbuds and (4,5,6 & 8) labeled on the black poly bags. There are three sizes of ear tips that come with the UA Sport Wireless: small, medium & large. Size medium on the earbuds. Size small and large in the black poly bag. The first time you change the enhancers the material might feel a little stiff. Please make sure to align the funnel of the enhancer tip over the small speaker screen of the headphone casing. To change sizes, remove both the pre-installed ear tip and fit enhancer, starting with the ear tip. When removing the parts, always grab from the base and be careful not to rip the rubber material. Based on your initial experience, identify which size combination may be a better fit. Each size should be clearly labeled in an individual baggy inside your original packaging or you can find the size of the fit enhancers on the inside with a raised stamp marked with either ‘R’ for Right or ‘L’ for Left along with the numbered size. Most people use the same size for Right and Left but it is possible to use different sizes because some ears are not symmetrical. First, align the sound tunnel of the headphone with the hole in the fit enhancer and gently pull the outer edge of the adapter over the edge of the speaker. Next, align the inner grooves of the ear tip with the grooves in the sound tunnel and gently push the ear tip into position. Try a variety of combinations between the enhancers and ear tips to find the best combination, providing comfort, superior sound quality and secure fit. If you’re still having trouble finding the best fit, please contact customer service at jbl.com/contactus