Yellow Mountain Imports Yunzi Go Stones, Double Convex, 11.6 Millimeters (Size 41) This Yunzi Go stone set includes 181 black and 180 white 11.6-millimeter (size 41) double convex stones; each stone measures 11.6 millimeters in thickness (approximately 0.5 inches); the edges are rounder and fuller than smaller Go stones to accommodate the extra thickness; even with the added thickness, the width is still a standard 21.5 millimeters wide, so these stones will occupy essentially the same space on a Go board as the thinner stones Yunzi stones have a balance and a deeply rich color that are instantly noticeable; the stones will actually look nicer over time as they absorb moisture and natural oils from the fingertips; they also leave an audible ''snap'' as you place them on the board; these stones are coated with a gloss finish The texture, symmetry, and precision of these Yunzi stones are superior; these stones are double convex meaning both sides are fully rounded Yunzi stones have been made for almost a thousand years in the same area of Yunnan province in southern China; if you have not played with Yunzi stones before, you will discover playing with them is a completely different experience than playing with glass or plastic stones; playing with Yunzi stones clearly enhances the experience of playing Go 30 day return policy; here, at Yellow Mountain Imports, we want you to be satisfied with your purchase; you are backed by our 30 day no questions asked money back guarantee so you can buy with confidence