The distances is between 12 and 15ish inches from basking spot. So it allows you some
space to work with inorder to get the temps worked out to proper range...an it will
work with different climates.
They make a lamp stand to hang them from but with 8+ viv's that could get expensive
I personally don't use the screen so mine are mounted like this.
We just attached a peice of wood to the stands to clamp it to.
Note: The second hood in this one is for an extra white household bulb to raise heat
during Winter....and for a CHE (Ceramic Heat Emitter) during Winter nights when our house
does drop below 65*.