Is the Mo Fi Sinatra Box Ses stereo or mono

Dear all,

I know this question makes me seem dull, so I apologize in advance.

I recently purchased the mo fi Capitol Sinatra box set (silver box, numbered, etc.). I can't tell if the records are stereo or mono. I have checked the box, and the blogs, etc. and I can't figure it out. I have tried to determine by listening, but I still do not know.

Can someone out there tell me how to make this important determination?

Regards,

Erick