In summer we sweat a lot, so we have to drink more water. It is OK to drink normal water but OS-1 is better than normal water and Aquarius. OS-1 is 経口補水液。経口補水液 has some salt and glucose. If you have heat illness, you have to take some salt and glucose. These materials help you to be better. Additionally, it prevents that you get heat illness. This summer is also very hot, so we are careful that we get heat illness.