Yellow Mountain Imports Melamine Single Convex Go Stones, 21.5 to 22 Millimeters (Size 3) Full set of Go stones; 181 black and 180 white stones Size 3 Go stones; 21.5 to 22 millimeters (size 3) single convex stones; each stone measures 5.6 millimeters tall x 22 millimeters wide (approximately 0.22 of an inch x 0.87 of an inch); these stones will fit Chinese and Japanese standard sized boards Go bowls; 2 plastic bowls (gosu) to store Go stones are included in the set Durable; melamine is an exceptionally durable compound commonly used when strength is essential, such as in kitchen counters and industrial applications; these are excellent stones to use for constant, frequent use; like Yunzi stones, they have a satisfying heft and snap to them; great for Go clubs, starter sets or as a substitute for when you do not want to use your expensive set of stones 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 Go Stone: 0.22 x 0.87 of an inch (5.6 x 22 millimeters) approximately This set includes 181 black and 180 white single convex 21.5 to 22 millimeter (size 3) Go stones. These are excellent stones to use for constant, frequent use since they are produced from melamine, an extremely durable material. You will not,however,compromise the pleasure of play for durability since these stones have a good weight and snap reminiscent of the highly revered Yunzi stones.