Kowalski Okna Eternalline STV windows use a three-fold sealing system with Hard Rebate, STV dry-glazed tape, and composite reinforcement. STV bonds the insulated glass to the sash rebate with tape so the unit stiffens the sash on all four sides. The Plus line is 82.5 mm, 6-chamber, with tilt-and-turn RU hardware.
Kowalski Eternalline STV: three-fold sealing with Hard Rebate, STV dry-glazed tape, composite reinforcement (much lower conductivity than steel).