Features:    * Using laser sensor, direct measurement, more convenient than mechanical sensor.  * The size of the split sensor is small, which is suitable for measuring in a narrow space.  * Two kinds of sensors selectable, the integrated sensor and the split sensor.  * Metric or imperial units can be used to display readings.  * With automatic power off function.    Measuring Principle:    This tensiometer can measure the natural vibration frequency of the belt through the emission and reception of the laser, and then calculate the tension value of the belt by combining the input belt mass and the free belt length.    Specifications:       Measurement Range    10Hz~800Hz        Input Range    Free Belt Length Max 99.99m            Belt Mass Max 9.999kg/m        Digital Sampling Error    <1%        Display Error    ±1Hz        Total Error    <5%        Operating Temperature Range    +10°C~50°C        Transportation Temperature Range    -5°C~70°C        Unit of Measurement    Metric: m, kg/m, N            Imperial: Inch, lbs/foot, lbf        Optical Path Measurement Distance    3mm~20mm        Depth of Split Sensor    About 66mm        Power Supply    4x1.5V AAA (UM-4) Battery        Size    Main Unit: 178mmx72mmx34mm            Sensor: 124mmx2mm1x12mm        Weight    180g (Not Including Battery)        Standard Accessories    Main Unit            Split Sensor            Carrying Case (B04)            Operation Manual