Sikaflex-221 adheres well to a wide range of substrates and is suitable for making permanently elastic seals with high adhesive strength. Suitable substrates are materials such as metals, metal primers and paint systems (two-component systems), ceramic and plastic materials. Seek manufacturer's advice and perform tests on original substrates before using Sikaflex-221 on materials prone to stress cracking. This product is only suitable for experienced professional users. To ensure adhesion and material compatibility, it is necessary to perform tests with the substrates under real conditions.