The shell is made of environmentally friendly plastic nylon 66. The contact piece is made of high-precision copper, which is an environmentally friendly hardware material, and the surface is treated with environmentally friendly anti-corrosion treatment. The outer shell is resistant to temperatures greater than 160 degrees Celsius and cold-resistant to minus 40 degrees Celsius. The best working environment is minus 20 degrees Celsius to 80 degrees Celsius in moisture-proof and ventilated facilities.