Barska® Front Sight with Integrated Red Laser. If you want a laser but don't have the rail space or don't want to overload your AR, your search is over.
This handy two-fer attaches to any picatinny or Weaver rail to provide laser precision and with easy windage / elevation adjustments. Rail length: 30mm. Total length: 2 1/2" l. Weighs 3.2 ozs. Includes 3 x LR 44 batteries.