Buying a full size Chinese 12K hone...
This ad is for a 2" wide x 4" long Chinese 12K hone, and is not a full size Chinese 12K (C12K) hone. If you can afford the current price at Woodcraft (or other vendor sites) for the full size hone of about $35, you should buy it. Here's the link to the full size product.
Buying the quarter size Chinese 12K hone...
I purchased the above hone, and sliced into four pieces. It is about 1/2" thick and about 2" x 4" in honing surface. (The back side has saw marks, is not entirely flat, and is not suitable for honing.)
Add $5 if shipping outside the US.