Insulation glazing is included in many window systems that differ in their frame materials (wood, metals or plastics). The main functions of the glazing - heat and sound insulation - can be achieved only with high-quality sealing techniques and materials. A new sealing system is described, which provides for the desired physical properties of insulation glazing. Sealing is provided by two-component butyl/polysulfide compositions. Those seals enjoy a stable and ever growing application in various window systems.