:The Kiwi Ears Airoso incorporates innovative technology to deliver an impressive sound experience. With a combination of physical and RC crossover technology, it ensures a smooth, precise frequency response across the full spectrum. This technology minimizes interference and optimizes sound clarity, allowing you to hear every detail with unparalleled accuracy. DUNU S&S Eartip is availble in 4 options according to the eartip size: S/M/L, S, M, L, which can meet most people's needs.