Interdental brush!

I use the smallest size, SSS! I always use this before brushing my teeth! My teeth are on the thinner side, so I use the finest size. I buy them at Daiso, and a pack of 8 only costs 2,000 won. It's a must-have when traveling too! I feel like my teeth only feel refreshed if I use it when brushing. I only have one left now, so I need to go buy more... I recommend it!