600w light set up

how does this heat shield work because it looks like it could just block the light
http://www.basementlighting.com/Merchant2/merchant.mv?page=1/PROD/HEAT1http://www.hydroponic-supplies.co.uk/heat-shield-small-69-p.asp
and would that heat shield go with this light
http://www.basementlighting.com/Merchant2/merchant.mv?Screen=PROD&Store_Code=1&Product_Code=HRLP
too start off 4 plants until they grown enough to be efficient to use 600w grow light how many 125w cfls would i need and how long would i have to grow em before using 600w im new to this as you can prob tell

I would not use that heat sheild, it will block the light. I would go with an air cooled reflector. You dont need cfls. You can use the 600w when the plants are babies as long as the plants do not get too hot.