This is simple instrument to check similar sensation at varying lengths. It is essentially a caliper, the jaws of which has two pointed extensions. When the caliper is closed and the extended jaws are touched firmly on forearm of a person who has been asked to close eyes, it gives feeling of a single point touch. Even when the jaws are slightly opened the feeling remains the same. Only at a significant distance does the subject realizes the touch as two point.

This is simple instrument to check similar sensation at varying lengths. It is essentially a caliper, the jaws of which has two pointed extensions. When the caliper is closed and the extended jaws are touched firmly on forearm of a person who has been asked to close eyes, it gives feeling of a single point touch. Even when the jaws are slightly opened the feeling remains the same. Only at a significant distance does the subject realizes the touch as two point.