Surveyors use these items to align the compass and measure the vertical and horizontal angles for accurate measurements while developing their topographical maps. This is a perfect item for illustration and functions of theodolite.Total diameter of alidade: 7 Inch. Color: Antique finish (wooden alike). These unique products made by Indian handicraft artisans. It is a Unique gift item for those who have a unique choice. SPECIAL DISCOUNT FOR WHOLESALE & BULK INQUIRY!