The heat mat will keep my seed trays about 20 degrees warmer than the surrounding air. In my shop that is around 80 degrees.
The LED grow light is about 2 inches above the top of the plants.
I bought some grow light hangers with ropes so I can move it up as the plants grow.
You don't need the light until the seeds sprout.
It's on a timer set to be on for 16 hours then off for 8 at night.
We planted a bunch of flowers and vegetables and the germination rate was great.
The corn was 90% successful.
My wife had flowers sprouting in less than a week.
Last spring I saw the complete kit with a grow light and a heat mat on sale for $29.99.
https://www.amazon.com/gp/product/B0098R0600/?tag=skimlinks_replacement-20
https://www.amazon.com/dp/B074753J5V/?tag=skimlinks_replacement-20