Wiśniowski manufactures steel internal doorsets at Wielogłowy near Nowy Sącz, including its technical fire ranges at EI 30 and EI 60 in standard and enhanced variants. The range is covered by Krajowa Ocena Techniczna ITB-KOT-2017/0079, fourth edition, issued by Instytut Techniki Budowlanej in August 2025 and valid to August 2030, held in the company’s own name and also covering large-format fire doorsets. The company is one of Poland’s largest door and gate manufacturers. Note that the fire range is sold through the industrial channel and is not featured on its consumer-facing site, so the assessment in ITB’s register is the evidence relied on here.