Good Used Triad N57MG, 115 VAC to 115 VAC, 3 wire cord & socket isolation transformer. Shield is grounded to core. Rated at 500VA, 4.35 amps. My father bought this sometime in the early 1970s. I got it after he passed in 1997 and haven't used it except to test that it works. Shipping weight is 28 lbs but it will fit in a USPS priority mail medium flat rate box.