Product description: a cap shell material: two sides of ABS engineering plastics (including flat-topped helmet, V word helmets, helmets, etc. spire) has three accessory mounting holes lined architecture: six, single ribbon connectors After locking hoop ways: ● knob ● ● Plug-in push-button next to impeach with furrowed ways: ● ● sliding adjustment buckle adjustment Features: 1 with shock, electrical insulation, heat resistance, chemical resistance and other properties. 2 matches GB2811-89 standard 3 for electric power, chemical, petroleum, construction, forestry, port, municipal and other industries colors can be optional (the national standard color)