The entire range has special anti-dust air intake filters to guarantee a long operating life. 整个系列有特别的防止抗灰尘吸入的过滤器保证有长的工作寿命。
A bulb at the connector end provides a reservoir of filling gas which is necessary to give a reasonable working life. 在连接体的末端有一个小球,用以贮存所充的气体,其目的是为了使计数器具有适当的工作寿命。