Audio output transformer products for tube amplifiers are manufactured in Vietnam. Core material is imported from nippon. The wire we use is exported to Europe and America. We use new materials and do not reuse them under any circumstances. The high skills of Vietnamese workers have created products with stable quality measured by the keysight machine system. Recommended for use with 300BSE, EL34SE, 6l6SE… Or bulbs with equivalent impedance and capacity. Inductance at 20Hz: 20 Henry. Total weight 3.2 kg (7 lbs). Bandwidth 20hz – 20khz (-0.7 db). Note : The price for 1 pair as shown in the picture. We ensure careful packaging.