Yellow Mountain Imports Yunzi Go Stones, Double Convex, 9.2 Millimeters (Size 33) This set of professional Yunzi go stones is China's finest; this set includes 181 black and 180 white 9.2 millimeter (size 33) double convex stones; each stone measures 9.2 millimeters tall and 21.5 millimeters wide (approximately 0.36 x 0.85 inches); these stones will fit Japanese, Chinese and Korean standard size boards The stones will actually look nicer over time as they absorb moisture and natural oils from your fingertips; Yunzi stones have been made for almost a thousand years in the same area of Yunnan province in southern China The texture, symmetry, and precision of these Yunzi stones are superior; these stones are double convex meaning both sides are fully rounded; if you haven't played with Yunzi stones before, you'll discover it to be a completely different experience than playing with glass or plastic stones Yunzi stones have a balance and a deeply rich color that are instantly noticeable; they also leave an audible ''snap'' as you place them on the board 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