legal limit is net 35% so they use a 43% hp charcoal to guarantee it passes mass inspection
I guess it depends on what version or model/line of tint you get. I have Solargard and its 35%. But dont know what line it is but more than likely top of the linehttp://solargard.com/index.cfm/fuseaction/Auto.HP_Charcoal/Auto-HP-Charcoal.htm
They use the 43, 22, 13, and 6......my old car had 22 but ended up having to rip it off to get sticker cause mass got so strict all of a sudden....sucks but i dont want to get it retinted every yr.