The three binocular numbers refer to its magnification power and the size of the objective lens. The number may look like 10-30X25 or 10/30X25. The dash on the numbers means that the binoculars are zoom binoculars, while the slash means that the binocular has two sets of eyepieces. The numbers 10 and 30 indicate that the binoculars can magnify an image 10 to 30 times. 25, on the other hand, refers to the size of the objective lens, in this case, 25 mm.