ArmaLite's exclusive forged-steel clamp-on front sight base allows the shooter to zero the front sight so that the rear sight is perfectly centered.  Massive clamp screws hold the base tightly in place without the bore deformation that is common to the usual, difficult to service pins.  No pins allows this sight to be easily reusable. 

.750 Journal

Clamp on A2 sight kit includes screws.

Does not include Front Sight Post, Front Sight Spring, Front Sight Detent

Tech Note 53: Adjusting ArmaLite's clamping front sight base for windage