Ready to go: the Sennheiser stereo earphones MX 75 with Twist-to-fit system ensure best possible fit. These earphones are specially designed for sporty activities. We developed a new way of securing an earphone in the ear: fitting the earphone by placing it in the ear and hooking it with a slight twist into the back of the conca. Three sizes of rubber rings (S, M, L) allow for secure and comfortable fit for different ear sizes. The casing is infolded with a very robust, sweat and water resistant, milky white TPE material. Powerful neodymium magnets ensure a high fidelity sound.