These handles are buffalo horn. I just removed the handle last week. As far as quality goes, the handle itself is constructed well. I used it as a replacement on a knife that originally came with plastic.
The installation is not fantastic. It's functional for a home cook but came loose after 6 months use in the restaurant. It just needs knocked off and some better epoxy applied to the tang to secure the handle a bit better. This knife is well worth the money and is extremely stain resistant.
Here is a link to some more pics. This is my 240mm which measured 258mm ootb. Very large blade which I personally favor. tanaka-ginsanko-wip-t2029.html