For decades the steel door series S4 offers protection against several threats worldwide. In this spring, the door was additionally tested according to the European standards for fire resistance. The steel door offers protection against forced entry (up to RC4), ballistic (up to FB7-NS and blast attacks (up to EXR5) and now additional security against fire up to the class EI90 (T90). Test video at https://www.youtube.com/user/saelzersecurity. Several variants, single and double door with/without glazing, were tested from both sides of the door according to the current standards at an accredited testing institute. The S4 steel door is used in many areas. Owner and architect can individual compile the door in consideration to the security, architectural and legal requirements (modular construction systems).