What tool is used to determine skin fold measurements?

Skin fold caliper

Explanation:

It is used to assess the skin fold thickness. It is based on hypothesis that fat is equally distributed over the body and thickness of skin fold is a measure of subcutaneous fat. It is used to predict the total amount of fat in the body. Basically four skin folds are measured to estimate the body fat namely, biceps skin fold, suprailiac skin fold, triceps skin fold, subscapular skin fold.