The 178GT is isolation transformer with primary 120VAC, 50/60 Hz. and Secondary 120VAC. Toroidal transformer are for high isolation, low noise, light weight, cool operation and low profile. Standard 3-wire, grounded plug (for use with adaptors for proper grounding). Input (primary) connected to a 5 foot long cord & standard North American plug (NEMA 5-15P). Output (secondary) connected to two standard - 3 wire grounded receptacles (NEMA 5-15R). Features include ventilated black steel case, rocker lighted on-off switch & circuit breaker protected output.