only acrylic can truely block off almost 100% harmful UV rays.....but they cannot withstand the heat from the MH bulbs......
there is only one model that either lexxan or plexiglass has that has high temperature tolerance...but singapore does not have that model of acrylic....even dama plastics dun have....
so if you are talking about glass...either the glass has a permanent coating on the glass like our specs to reduce UV or is a laminated safety glass with some UV filtering properties...
all those tempered glass, frosted glass, all actually does not filter away much of the harmful UV....to my knowledge that is..but i may be wrong..hehe