... even color ,well -structured electrogalvanized sheet.2. Brush bristle uses nylon yarn with characteristics like high flexibility,strong elasticity ,wear- resistant ... -frcc ,No radiation , non -toxicity ,low smoke .low calorie.3.Nylon density 1.14, melting temperature 218-224°c, heat deflection ... ,white smoke ,pale blue flame inner ,yellow outer layer. door and window energy-saving brush