Shop door shopping help!

[mcclellandj]

Looking for a walk through door for my shop that looks like the existing so that I can add it to the side of my shop. Or recommendations on something better.

 

[nadogail]

I used a prehung fiberglass door, it was installed about 20 years ago.

 

[Fav Onefour]

I used a prehung fiberglass door, it was installed about 20 years ago.

I don't know if that is an option for @mcclellandj . The existing door is an oddball if they want a direct match.
The door looks similar to an enclosed trailer door. It appears to be skin over a frame and there's no threshold. I'm wondering if it is built by the building manufacturer?