Features: 1. Memory foam material, breathable, soft and comfortable 2. Knead the memory foam to a small size (about 5 seconds of rebound time), and then insert it into the ear. The sponge will slowly expand and fill up according to different ear canals, which has a certain sound insulation effect. 3. Suitable for 5-7mm diameter earphone plug 4. Three sizes of ear caps can be replaced at will according to your own needs 5. Equipped with storage box, easy to carry and store