More than worth it....
Multiple uses.
Seperate veg/flower rooms
Line walls
make rooms
doors
line floors
cover Bucket pots for lightproofing
I swear by it. I couldnt have my split closet without it. And Ive seen 100ft rolls for $70 online.
Copied info on reflectivity.....
.........White/Black plastic (also known as panda plastic or "poly"):
"Poly" is useful if you are setting up a temporary grow room or don't want to damage the walls. Poly is easily cleaned.
The purpose of the black side is to not allow any light to pass through the plastic, which ensures your dark cycle remains dark. The white side is 75-90% reflective. Choose a 6 "mill" thickness of poly for maximum light blockage and duribility.
If this plastic is put too close to the light, you will obviously melt it so be careful!. Panda plastic does not create hotspots. Poly can be attached to the walls by using carpenter's nails or using tape glue or similar means. This can be used as a cheap alternative to mylar if painting your grow room is out of the question.
Contributed by: DaChronicKing