The settings (hi med low) allow for different levels of light for different growing purposes. They are bright and certainly work for the plants to grow.

These are a great substitute. As you can see the strip is for 2. Ordered 3 more. Would recommend these.

Do not use this for growing seedlings. At 6 inches, on the brightest setting, it only puts out between 50-60 foot candles. Foot-candle output diminishes greatly more than an inch from the light. Light hangs down touching plants.