What makes a Double bass good for Jazz or Classical?

[Ken Smith]

Originally Posted by Pongsak Sooksawak

Here, I took those pics since I got this baby.
And, my bass has some kind of nail made from ebony wood in the corners (near f hole), like all basses imported to this regian (south east asia). For example, my friend's Hawks has the same thing.

Ps. It located in Bangkok, Thailand.

Ebony nail near the F holes? Can you show me a picture of that? This sounds confusing!