Apparently there is a vent hole on the under side of the switch.........I've taken the top off as instructed, blown in it & it's airtight. My husband also tested it & it's airtight. Neither of us is noticing ANY sort of vent holes on the under side of the switch. I encourage ALL of you SB owners to take the top off the SB & try blowing in it........if it's airtight.......then there really is NOWHERE for that battery to blow. (I do notice there is a hole in the black area before you reach the switch......but this will NOT allow any battery to vent.) My husband is currently drilling 4 vent holes near the bottom of the SB so that if something happens the ventilation will be equal in all directions. Please check your mods.