then buy it jon!!! I just got a fat set up offa htgsuppy, 6' inline fan, cooltube, digi 600w ballast, hps600, mh600 conversion...and 25ft of mylar. haha that 5% will always get me and those smooth sheets if you keep em smooth are the bomb, and 5.0
poly is, 90% reflective mylar, 95% reflective. mylar is some of the most reflective stuff you can buy (why so many use it) but if your not good with working with it, that black and white poly is a great alternative. You can also just get flat white paint and paint your walls. The poly is like hanging tarp on your wall, seems like a little more protection, but that mylar can be wiped clean just as easy. Hiphip HOORAY!!!