Length: 30 cm 
Material: Stainless steel - extremely durable and can be used for a long time
Built-in electronic angle sensor to  measure the angle of inclination 
Relative angles can be measured by setting the measured angle to zero before measuring in any desired position 
Can be unfolded till a maximum angle of 180 degrees
Compact and lightweight design for easy storage and transport
Automatic shut-off when ruler is not in use to conserve battery life 
Power supply: 3V, 1 x CR 2032