Features 
1.the prefilter can effectively remove moisture lampparticles to imporovr the stability of reading
2.Zero automatic tracking,long-term use is not affected by zero drif 
3.the Chinese and English interface can be selected 
4.the selection of oxygen,humidity and data acquisition function can be provided
5.Sound and light alarm,vibration alarm,sound and light vibration alarm and close alarm are avalible 
6.It can store up to 100000 date.