| 摘要 |
The filter, designed to be fitted into each nostril, comprises a foam cylinder (1) topped by a round plate (2) made from rubber and having a central hole (3). The hole in the plate can have a tubular extension which fits inside the foam cylinder, in which case the plate has four additional small compensating holes (4) round the central hole. The foam cylinder is, for example, 1.5 cm in height and 2 cm in diameter, with the plate 1.5 cm in diameter.
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