This is a transformer for voltage doubling rectification. It was used in a KT-88 single-ended amplifier. It's an old item. It looks clean at first glance, but only the top and bottom plates have been lightly repainted. It was in use, so there are no operational issues. The unused terminals have been checked for continuity with a tester. The screw hole spacing is approximately 85mm on the long side and 69mm on the short side, as measured. --- Below is the Mercari AI-generated text --- Metal box-type parts for vacuum tube amplifiers, highly durable. - Color: Black - Shape: Box-shaped - Features: Metal case - Application: Vacuum tube amplifier parts