 The AR-15 can also mount a scope on the carrying handle.With the advent of the AR-15A2, a new fully adjustable rear sight was added, allowing the rear sight to be dialed in for specific range settings between 300 and 800 meters and to allow windage adjustments without the need of a tool or cartridge.Current versions such as AR-15A4 have a detachable carrying handle and use Picatinny rails, which allows for the use of various scopes and sighting devices.