双耳受话器
bi-telephone
double tail-phone receiver
按钮电话受话机
push button telephone receiver
半沉头机器螺钉
oval countersunk fillister head machine screw
镀镍低碳钢平头机器螺丝
nickel-plated mild steel countersunk head machine screw
镀镍低碳钢圆头机器螺丝
nickel-plated mild steel round head machine screw
镀锌沉头机器螺丝
galvanized mild steel countersunk head machine screw