FFP Brief Introduction: Most scopes have the reticle fitted in the second focal plane (near the eyepiece).
The reticle increases its size when change the magnification from low to high
Each system has its advantages.
The advantage with telemetric reticles (like rangefinder & Mil-dot etc) is that the target image and distance between dots remains constant even when changing magnification.
It is the system that is widely used by the TOP military suppliers now.
100% waterfroof tested
100% fogproof tested
100% shockproof tested to 1200G