Pre-Engineered Windows in Bangalore (TOSTEM) Japanese pre-engineered windows provide higher safety and security. Tostem uses innovative configurational approaches and structural ideas. Window fabrication, like pre-engineered structures, takes place in a production plant, with only assembly taking place on-site in a relatively short amount of time. Our team consists of professional employees, experts, engineers, and project managers who oversee and assure quality. Architects designed pre-engineered windows to reduce dust and noise.