Shaped in an oval following the aspect ratio of the human wrist, it provides a more accurate measurement for wrist accessories such as oval bangles and watches. Made from sturdy PLA plastic. Stepped design provides quick and accurate measurement vs conical designs. DOES NOT DAMAGE JEWELRY unlike metal sizers. Much better than folding plastic sheet mandrels that keep disintegrating! Manufactured in the USA Lifetime warranty Mandrels provide accurate measurements when measuring objects that are meant to be circular such as bracelets or necklaces. For these items, do not use straight rulers as they do not factor in the inner circumference of an object and will give longer, deceptively false measurements. Avoid upset customers and measure with a mandrel! Bracelet Sizer / Watch Mandrel Oval (Aspect Ratio of Human Wrist)