ESS Speaker AMT HEIL Ribbon Replacement Diaphragm ESS AMT-1A, 1B, 1C, 1D, 689-1107 ESS AMT Speaker HEIL Ribbon Diaphragm Part # 689-1107 Original factory ESS Part Hand folded, USA made Size: 1-9/16" x 5-9/16" (40mm x 141mm) Impedance: 4 ohm, DCR: 3.7 ohm