Unused, new old stock older series Konosuke GS from before the thinner harder GS+ Series with the chestnut handle. These are a bit thicker with more convexity, a little softer than current production and a bit tougher. From a collection purchased at Bernal Cutlery between 2013 and 2017  in unused condition with original box

Thin light hamaguri convex ground SLD steel core with stainless cladding with octagonal ho wood octagon handle.

This has been recently handled with an old stock octagonal ho handle with a horn ferrule, the same handles these were originally made with, with the same small machi gap. 

Konosuke GS+ series knives are a thin convex ground three layer san mai forged blade with a stainless cladding and a semi-stainless/stainless SLD core. SLD steel is an improved SKD11 steel most commonly used in tap and die tools and metal stamping dies. It is designed to stay tough when treated hard and to retain its workability at a high hardness as well. For knife making this translates to a very long lived tough edge with near stainless or stainless properties; it holds an edge well and even cuts well as it dulls.