First Focus Plane(FFP): FFP scopes place the reticle in front of the erector. They are more specifically designed for tactical shooters and hunters where the distance to target changes and is often unknown. With an FFP reticle, the size of the reticle will appear to change as the scope’s magnification is changed. And it helps with calculating bullet drop and wind calls.

Specifications:

Magnification: 4-16x
Objective Lens Dia.:44mm
Tube Dia.:30mm
Adjustment Click Value: 1/10mil or 1/4moa
Reticle: mil or moa
Illumination: N/A
Field of View: 26.2-6.55 Feet @ 100 yards
Eye Relief: 85-90mm (3.4-3.5 inch)
Exit Pupil: 2.75-11.0mm
Lens Coating: Fully multicoated
Parallax Setting: 100 yards
Focus mark: 10, 15, 25, 50, 100, 200, 500 and infinite
Finish: Matte
Distance between objective lens part and middle turret: 40mm
Distance between middle turret part to power ring: 32mm 
Diopter compensation from fast-focus eyepiece (+2 to -2.0)

Main Features:

30mm Monotube.
1/10 MIL or 1/4moa  windage and elevation adjustments for fine-tuning accuracy.
Ultra Short 270mm 10.3"
4" Long Eye Relief.
Turret lock sytem. Pull to adjust, press to lock.
Side Focus starts at 10 Yard.
Fast-focus Eyepiece for quick and easy reticle focusing
O-ring Sealed and Nitrogen Purged Ensure Water Resistance and Fog Proof performance; Shockproof to 750g. Waterproof at 1 m.
High quality 6061 T6 aircraft grade aluminum alloy with durable black matte finish.