Widely Compatible: These earplugs have a 3.8mm wide opening, compatible with earphones that use 3.8mm‑5.5mm sound holes, and are compatible with most earphones. Item Type: Earplugs. Application: The inner tube aperture of this earplugs is 3.8mm, suitable for headphones with a sound guide hole of about 3.8mm-5.5mm.
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