Magpul® MBUS Back Up Rear Sight, Gen 2

(46 reviews)
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Magpul MBUS Back Up Rear Sight, Gen 2

The new MBUS (Magpul Back-Up Sight) GEN 2 is a low-cost, color injection molded, folding back-up sight. The dual aperture MBUS Rear Sight is adjustable for windage and fits all MIL-STD-1913 Picatinny rail equipped weapons, but is specifically tailored to the AR15/M16/M4 platform.

Made in the U.S.A.


  • Impact resistant polymer construction provides light weight and resists operational abuse
  • Spring-loaded flip up sight easily activated from either side or by pressing the top
  • Detent and spring pressure keeps sight erect but allows for unobstructed folding under impact, etc.
  • Clamps to any MIL-STD-1913 Picatinny/STANAG 4694 receiver rail and provides the same height-over-bore as standard A2 irons
  • Protective wings shield the dual flip apertures
  • Detent knob easily and positively adjusts windage


  • Weight, w/ hardware: 1.3 oz.
  • Height above rail, stowed: ~0.51 in.
  • Length, stowed: 2.6 in.
  • Length, deployed: 1.5 in.

NEW Features for GEN 2

  • Reduced size for greater optics compatibility
  • Both small and large apertures are on the same plane


  • 5
    Magpul never lets you down

    Posted by Jason Scheerens on 12th Jan 2015

    Love the sight

  • 5
    excellent sights, for the price

    Posted by Jon on 28th Sep 2014

    back up rear sights are very pricey. however, if you're in a pinch like I am, these Magpul sights are pretty good. They sit pretty snug on my Colt upper. I haven't tried it out myself, but I've been told that these sights retain zero after being dropped on. Take it for what it's worth, but for a price point like this, you really have nothing to lose with these Magpul rear sights.

  • 4
    Back up sights

    Posted by Adam Moseley on 3rd Aug 2014

    Quality piece of essential equipment. Great shopping and prompt order shipping.

  • 5
    Awesome sights

    Posted by David Keller on 30th Jul 2014

    These worked really well, easy to install & easy to zero. Good as back up sights if my EoTech goes out.

  • 4
    good enough

    Posted by Unknown on 25th Jun 2014

    A little bulkier than Troy's or similar iron sights but also half the price. Switching between the two apertures is also a little more difficult than iron sights because they snap together. Gets the job done.

  • 5
    Great as primary or secondary irons on a budget

    Posted by Unknown on 14th Apr 2014

    So you have a shiny new rifle. Now you need sights. That EOTech is great until the batteries die. Backup sights are a must. These are great. Plastic. Made in the USA. And spring operated. When I put them on my rifle and shot it for the first time I didn't even need to adjust elevation or windage. Your mileage may vary. It's important to note that the rear piece can be adjusted for a larger sight picture. This comes in handy with CQB, low light and general crappy eye sight. SKD shipped fast and cheap. Thank you Magpul and thank you SKD.

  • 5
    Rear sights

    Posted by Unknown on 10th Jan 2014

    SKD has great sale prices

  • 5
    Great sights

    Posted by DS on 1st Feb 2013

    I have Magpul BUIS on all of my ARs. I have used other BUIS's by troy, midwest and dpms and these hold the same standard of those while being both lighter and MUCH CHEAPER!

  • 5
    very solid

    Posted by Nicholas Gentile on 30th Jan 2013

    Was better than i thought it was going to be, fits great. Peep hole is very clear and works well with both eyes open. Co-witnesses perfectly with my dot site. To sum it up, worth the money! Perfect buis!