An important factor when choosing is the tightness of the structure. WP marking guarantees complete water resistance of the structure to a depth of 1 meter for 5 minutes. WR - stands for moisture resistance and allows observations in high humidity conditions. Many manufacturers produce optical devices filled with inert gases, often using nitrogen or a mixture of argon and krypton gases, which completely eliminates lens fogging in conditions of high humidity and sudden temperature changes.

When choosing, it should also be noted that there are passive monoculars and active ones. Passive ones are suitable for observation in almost any light, except for complete darkness, while active ones with IR illumination allow observation even in the complete absence of light.