First, use: 
This instrument is a precision, high accuracy and durable, designed to test the softness of the leather, as are a variety of leather testing footwear, furniture, clothing and other essential equipment. 
Second, the principle: 
The instrument uses a small pneumatic valve load force on the probe and fall according to a certain speed, naturally pressed against the seat leather folder on the test, by pressing arm pointer table read out the leather softness index