Green alligator strap on Rolex 118138

[komakino]

Hi there,

I recently purchased a 118138 Rolex that is a few years old. I'm interested in replacing the green alligator leather strap. Can I purchase the original green alligator strap online or do I need to send it to my local AD for replacement? Will AD replace the original alligator Rolex strap?

What is the part/article number of this green strap and its cost?

I noticed the strap has BSTD printed at the back. Is this a third-party brand? What brand is BSTD?

Thank you.