This is a set of 5 unused JETSTREAM ink refills. The part number is SXR-38, and they can be used in knock-type ballpoint pens such as the SXN-150-38. The tip size is 0.38mm, which I think is a convenient size for writing even small characters. The regular price is 100 yen per refill, so how about this great deal? This is a set of 5, but only one has been opened. All are unused, but please understand that they have been stored at home.