The MST 2.5mm Optical Zone Marker (Item #AR0370 2.50) is a purpose-built ophthalmic instrument in the Calipers, Gauges & Markers portfolio. Designed around its specific working geometry, it features 2.5mm diameter. Open circle tip with various diameter sizes and low profile design. Round Handle. Overall length: 95mm. This combination of thoughtful design details and clearly defined specifications helps surgeons quickly identify the configuration that best fits their preferred technique and procedural needs.