Metal Doumbek Tuning Rings, for 12 inch Drum Item Code: MD12-TR the smooth top ring with inside diameter of approximately 12 1/4 inches to fit over the drum head. The flat bottom ring has the tabs for the tuning bolts and is approximately 11 11/16 inches inside diameter. Fits the Metal Doumbeks: MD12, MB12, M12J. Hand made, sizes will vary slightly. Tuning bolts MDCP, MDCP-L and replacement heads SS12, SD12, SH12, SH12G sold separately.