Question about scheduling an interview for internship

I am in the process of replying to an invitation for an interview and there is a two day period in which they conduct these interviews. During these two days there is an 8 hour period where interviews will take place. Would it look bad if I say that I am available anytime during one of those days, or should I pick a specific time? Or would it be better to select a specific time and then add that im flexible?

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