Square Type digital Frequency Meter Descrition:Model:90°SF-144-3 SF-96-3 SF-72-3 SF-48-3> Pointer frequency meters are intended for measuring ... ~65Hz, 47~53Hz, 57~63Hz, 44~56Hz, 54~66Hz, 450~550Hz, 450~650Hz, 550~650HzCase: Non-combustile ABS plastic material is used ... for making SF series'external case,and PPO plastic material is ...