There are one inside caliper and one outside caliper, inside caliper is available in the same size range as outside caliper. Wide application, Can be applied for sculpture, pottery, tube and so on. The caliper is light and small, so you can easily carry this clay sculpture tool to somewhere. Excellent workmanship, smooth surface and edges without any burr. Made of stainless steel for superior hardness that reduce wear- outs and insure longevity. Features: - Steel calipers with hardened and finely polished tips for durability. - Inner caliper measures distance between aperture and surface. - Outer calipers measure the thickness and outside diameter of an object. - Lightweight and easy to handle, the calipers transfer measurements of internal and external dimensions from model to clay. - Ideal for measuring external and internal dimensions that cannot be reached with regular calipers, such as sculpture, pottery, and pipe. - Material: steel. - Size: 30.00X1.50X0.50 cm/11.79X0.59X0.20 in..Items from YU wen's store