The Flowtron Replacement Transformer is important for the zapping grid to keep working efficiently. The zapping grid is the only method of killing the insects. When the insects come near the bulb, the insects either get zapped and are killed instantly by the nearby non-clogging, high-efficiency shock grid. The Transformer enables the Flowtron Bug Zapper series of products to work continuously to ensure you and your family are safe at all times.