Details:

Specifications

Measuring Range*	10 - 800 Hz
Indicator error	±1 Hz
Total error	< 5 %
Sensing Distance***	0.200" - 1.6" (5 - 40 mm), typically (2.5"/60 mm max, depending upon ambient light & surface of belt to be measured)
Casing	ABS Plastic
Display	2 line LCD, 16 character per line
Input Range	free span length: up to 9.990 m belt mass: up to 9.999 kg/m
Belt Density	Belt Density (d = kg/m or lb/ft)
Belt Span	Min, approx. 10 cm (4 inch) Max, no maximum (as long as belt will oscillate)
Warranty	1 Year
Light Source	Red LED
Light Size	at 50mm - 6mm Square at 150mm - 15mm Square
Power Supply	9V battery
Metric Units	MASS must be entered in kg/meter SPAN in "meters"
English Units	MASS must be entered in lbs/ft SPAN in "inches"
Operation Video	https://www.youtube.com/watch?v=-l4-uG0JIAc&feature=youtu.be
Country of Origin	Germany

*BTM-400PLUS can measure up to 800 Hz, however most belts will break near 400Hz**Static tension (T) accuracy depends on the precision of entered values for free belt span (L), density (d) and natural frequency (f) of the vibrating free belt span, that has been plucked or struck, as noted in the relationship: T = 4dL2f2. Note that highest accuracy is achieved in the frequency mode where readings are accurate to <1%, ± 1 Hz.***Sensing distance can be extended when ambient light level is low also by adding a piece of reflective tape in the "target area" of the belt.