This low-profile transformer is unsurpassed in simplicity of installation and control. It features a toroidal core for more reliable, efficient, cooler and quieter operation. The clamp-type terminal blocks are far easier than the frustrating standard terminal blocks on other transformers. Just insert the stripped wire and close the clamp - it's done in seconds! Next, a VOLT innovation - the timer/photocell combination. Visible through the housing window, this timer can be set for simple dusk-to-dawn operation or set to turn off after a certain number of hours. The photocell is built into the timer. Slim Line Transformers have an easily removable, tool-less grommet to replace the metal knock-outs of traditional transformers. Traditional knock-outs on other transformers require tools and are difficult to remove. The grommets on the Slim Line Transformers are removed easily and can be replaced if necessary. To make this transformer slimmer, lighter, and simpler-to-install, we eliminated unnecessary voltage taps; just use the 12V and 15V taps. That's all you need for any medium-sized (up to 300W) LED landscape lighting system. No need to worry about voltage loss.