0.4mm interdental brush purchased at E-mart

This is an E-mart interdental brush. I went to the dentist for a scaling, and they recommended using an interdental brush, so I have been using it for several years now.

You can buy them at Daiso, or just buy a pack of ten or more at regular supermarkets. Using interdental brushes might feel awkward and uncomfortable at first, but once you get used to them, they definitely feel cleaner than dental floss, so I like them.