Theta Optics Open II Reflex Sight

Theta Optics
Code: THO-10-009053
  • Four Reticules
  • Red/Green Dot
  • Wide Field of View

A reflex style red dot sight with a choice of four reticules, red or green colour dot and a wide field of view through the lens.

Full description


This sight is an easy to use red dot which comes pre-installed on its' own 20mm RIS mount which will attach to any compatible rail system, accepting an LR44 battery near the front to power it. Like many popular ACM sights you have a choice of four reticules for different scenarios, which are selected by turning the easily accessible wheel underneath the sight. A set of rubber push buttons on either side control the colour and brightness of the reticule, and two Allen Keys are responsible for the windage and elevation adjust to line up your BB impact and crosshair. There are ridges at the rear of the sight which could be used as a backup ironsight should your main sight ever go down. This red dot sight offers a much wider lens than standard sights, giving you a much clearer view of the battlefield and reducing the likelihood that an enemy will get the chance to sneak up on your blind spot!


  • Red dot sight
  • Reflex style
  • Four reticules
  • Red/green colour dot
  • Windage and elevation adjust
  • Allen Key adjustments
  • 20mm RIS base
  • Accepts LR44 battery
  • Backup ironsight
  • Clear markings
  • Theta Optics branded

Package Includes:

  • Open II Reflex Sight
  • Allen Keys
  • Cleaning Cloth
  • Manual



Sight Type Icon
Sight Type
Sight Type Variant
Red Dot
Package Includes
Battery, Allen Keys,

Weight and Dimension

Product Height
Approx. 5.87cm
Product Length
Approx. 9.16cm
Product Width
Approx. 4.3cm
Weight KG Icon
Weight (KG)
Approx. 0.14kg


Colour Wheel Greyscale
Item Colour
Construction Icon
Alloy Body | Glass Lens

Sight Specific

Sight Magnification
Sight Adjustment Adjustments
Windage, Elevation, Illumination, Multiple Reticle Types,
Sight Zero Adjuster Method
Hex / Allen Key
Sight Zero Location
Top, Left,
Sight Mount Options
Integrated Rail Mount
Sight Objective Lens Diameter
Reticle Type
Multiple Reticle Types
Sight Backup Sight

Illuminated Sight Specific

Illuminated Reticle
Illuminated Reticle Levels
Illuminated Reticle Colours
Red, Green,
Battery Type
AG13 / SG13

Customer reviews

5 / 5
1 review for Theta Optics Open II Reflex Sight customer reviews
Written on 05/01/2021
Expected it to suck, really doesn't. Solid mount, easy adjustment with provided Allen keys. Adjustment seems to hold. Good brightness adjustment, multiple reticles, red and green options. Mostly use the red dot for better visibility. Not quite parallax free but pretty damn good and very impressive for the price. Definitely sped up target acquisition while plinking (airsoft being closed for the pandemic). Also had some very helpful advice on the phone, so thanks!
Rated 5 out of 5

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