Micrometers, also sometimes referred to as micrometer screw gauges, are measuring instruments that incorporate a calibrated screw for precise measurement of components in machinery. They are also used in telescopes or microscopes, and certain models feature a number of measuring modes for efficient measuring. Highly durable materials make these tools ideal for heavy use. Many models include positive spindle locks and friction stops. Digital micrometers feature displays that convert instantly between imperial and metric measurements. Dial caliper and micrometer sets are also available.