Marine electric alarm bells 船用防水警铃
Flameproof electric bells 隔爆型电铃
Electric alarm signal bells 电动报警信号铃
Bells, gongs and the like, non-electric, of base metal; statuettes and other ornaments, of base metal; photograph, picture or similar frames, of base metal; mirrors of base metal.
非电动的贱金属铃、钟、锣及类似品；贱金属雕塑像及其他装饰品；贱金属相框或画框及类似框架；贱金属镜子。
The prior various crossing adopt electric bells or ordinary transistor audible devices, and have the problems of difficult volume adjustment, large noise disturbance, etc.
目前各类道口采用的电铃及一般晶体管音响装置，存在着音量不易调整，噪音干扰大等问题。
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