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
    Best gear

    Posted by John Montes on 30th Dec 2019

    When you buy the front you gotta get the rear especially at these prices I wouldn’t buy anywhere else.

  • 5
    Good quality from Magpul

    Posted by Razor on 16th Oct 2017

    Good quality sight but over priced.

  • 5
    Great B/U sight

    Posted by James Miller on 21st Dec 2016

    Exactly as described and sale price made it a better buy than other lower priced sights of questionable quality. Needed this for a Dissipator upper (carbine barrel with rifle-length sight radius) and works fine. SKD lightning shipping a bonus!

  • 5
    Freaking awesome

    Posted by Unknown on 8th Oct 2015

    Mounted the back up sight and it was dead on. No adjustment necessary. Thanks Magpul. SKD shipping was awesome as usual. Ordered on Wednesday and received on Saturday.

  • 4
    works as advertised

    Posted by Unknown on 8th Oct 2015

    SKD's shipping was quick as usual. The sight was an extremely tight fit on the rail, had to be hammered forward (I tapped it forward with the handle of my multitool) to slide into place. Very good quality composite, screw fastens it into place. Very sturdy engineering. The flip up design decreases the sight radius (maybe 1") but it's only a backup for an optic anyway. The ergonomics are very good, sight can be flipped up just with a thumb toggle, without taking a hand off the grip. Sight is flipped back down quickly and locks back into place automatically.

  • 5
    What you need is here..

    Posted by Rocky Hernandez on 3rd Apr 2015

    Can't say it enough, best backup sights for the money. GOt them in OD for my IWI Tavor. Also have in FDE them for my Stag Arms AR15-2T 🇺🇸

  • 5
    Sturdy product, great price

    Posted by Andrew K SPD on 27th Jan 2015

    This is a great transition from a fixed sight to a flip down/up sight. And just the right price where you don't get junk and don't have to spend a fortune.

  • 5
    Good backup sight.

    Posted by Robert Schroeder on 26th Jan 2015

    It's a good backup sight for the money.

  • 5
    Great BUIS

    Posted by Zach on 15th Jan 2015

    As always, top notch Magpul kit!