The SUS-TAC Bubble levels are a designed to mount onto the scope on your rifle. 
 
Easy to install and simple to use, this bubble level provides the user with an indication of attitude of your gun when firing. Better accuracy and repeatability can be achieved through using this product.
It is available for all popular scope tube diameters and can be purchased in above and below bubble tube orientations. 
 
The bubble level uses a large bubble tube for improved visibility from the shooters position.
 
 
Specifications
      
Scope Bore  :       25mm, 30mm, 34mm, 35mm
Material of Construction  :       Aircraft Grade Aluminium
Size (L x W)  :       60mm  x 45mm 
Weight  :       +-21g  (0.75oz)   
Finish  :       Black Anodised
Liquid Color  :       Green