Many bloodstain examiners find this type of magnifier helpful when measuring and analyzing bloodstains. It comes in three different sizes and powers of magnification. Both magnifiers have easy-to-read, built-in scales and large lenses for easy viewing. It comes in three different powers, 5X, 7X and 10X. Each of these three magnifiers includes a metric scale, which is particularly useful for measuring blood spatter trails and areas. The 5X unit has a 2 1/2" diameter double glass lens and 4" diameter base, the 7x unit has a 1 1/2" diameter lens and 3" diameter base, and the 10x unit has a 1" diameter lens, a 1 3/4" base and 20mm scale. The transparent acrylic base on these magnifiers allows ambient light to illuminate the bloodstain or other physical evidence being observed.