Big Blue 17, that particular sheath is made from Wickett and Craig Tannery, skirting side leather split to 7/8 oz in pre dyed from the tannery color Brown.
I also use Chestnut which is about the same darkness, but with a slight reddish cast, Russet (natural light tan) and Black. I quit dying leather when I started using W&C and that was four years ago. They do have a web site.
Paul