smack-dab in the middle
Right in the middle or most central part (of something). There I was, smack-dab in the middle of Taiwan, with no money and no way to contact my family. You don't want the levels to get too high or too low. You need to keep it smack-dab in the middle.
smack (dab) in the middle
mod. exactly in the middle. (see also slap-dab.) Not too big and not too small. Just smack in the middle.