Fangrui Product Details Focusing Prism Spectroscope - If You Have Been Having Problems With A Fixed Focus Spectroscope This May Be The Solution You Are Looking For. This Spectroscope Has Been Used Throughout The World For More Than 35 Years Is Recognized And Respected By Gemmologists Gemmological Teaching Centers Worldwide. It Is An Ideal Instrument For A Small Gemmological Kit, Or Is Easily Carried In A Pocket. For Use At Antique Fairs, For Field Use Or General Study Purposes. Size:length:75mm (closed) Diameter:17.5mm Please Note:the Physical Slightly Color Difference Or Difference, Does Not Affect The Use, Please Do Not Mind, Thank You! Colour:black Material:metal Package Contents: 1 * Spectroscope Only The Above Package Content, Other Products Are Not Included. Note: Light Reflection And Different Displays May Cause The Color Of The Item In The Picture A Little Different From The Real Thing. The Measurement Allowed Error Is +/- 1-3cm.