15MM RETICLE WITHOUT A METAL RING. THE RETICLE IS A CLEAR CIRCULAR INSERT WITH A MEASUREMENT SCALE INSCRIBED ON IT. THE RETICLE SITS RIGHT AT THE FOCAL PLANE INSIDE THE EYEPIECE LENS OF A MICROSCOPE AND ALLOWS THE INVESTIGATOR TO MAKE MEASUREMENTS OF SPECIMENS

GIR 1&6 NOTE 2 (b) TO CHAPTER 90