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(SET) MFI SIG 556 Rear Diopter Sight & Rail with SIG SANs SIG 552 / SG-553 Style Non-Hooded Flip Front Sight (WITH Fiber Optic) (BLACK) / Price Includes Shipping via USPS Priority Mail

Designed specifically to fit the SIG 556 & SIG 551A1 Series Rifles & Pistols.

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(SET) MFI SIG 556 Rear Diopter Sight & Rail with SIG SANs SIG 552 / SG-553 Style Non-Hooded Flip Front Sight WITH Fiber Optic (BLACK)

Latest Production Run! New Lower Price due to higher volume manufacturing.

After years of RND and production difficulties I am happy to say that we have finally gotten to where I wanted to be in terms of quality and price. As many of you know it has taken us 8+ years to get to this stage.

The price you see above reflects the "Non Fiber Optic Version" with a Front Hooded Sight and all attachment hardware included.

What you see in the first picture is what you get in this set.

  • 1 - Black Diopter + Rail
  • 1 - Non-Hooded Flip Front Sight
  • 1 - Allan Wrench (for rail bolts)
  • 1 - Front Sight Windage Wheel, Nut & Roll Pin
  • 3 - Rail Bolts

This product is a True Plug & Play item. Just unscrew the 3 bolts that hold your rail on and place our rail on in it’s place. There are no small metal tabs or shims to lose as ours is 100% self contained. We also provide 3 replacement bolts and an Allan Key Wrench.

The Rear Diopter Sight had to be connected to a rail in order for it to be low enough to line up with the ultra low profile of the Original Swiss SIG SANs Front Sights. Yes you can use the Original PE90 / 550 / 551 / 552 / 553 Swiss SIG Front Hooded or Non-Hooded Sights. You can NOT use the SIG 556 USA Hooded Front Sight or any other sight on the market except our MFI SIG SANs Hooded or Non-Hooded front sights.

MFI REAR Diopter Sight & Rail:

I designed these to look like the original SIG PE-90 / SG 551 rear diopter sights that were welded on to the receivers. The parts are NOT exact copies of the originals... Meaning that the parts of the MFI Rear Sight are NOT interchangeable with the original Swiss SANs parts. The design did not allow this and it was more cost effective to not even try.

The Rear Diopter functions basically like the original and has near exact markings as the Swiss SANs sight housing. The numerical markings on the Drum / Diopter are also an exact copy of the original with the exception of the #4 which we changed from white to red... it just looked cooler.

As I am not a huge believer in the accuracy of the .223 / 5.56mm cartridge so I only fully tested the number 1 position at 100m. The #2, 3 and 4 designations may or may not be applicable. I did position the holes in the correct location, but I did not waste time or funds to test something I do not really believe in. While the #2 and #3 holes are the right size and position the #3/4 position hole is much smaller than the original and is NOT threaded for the insert of a target peep sight, nor is it likely to be at the correct angle as I do not have one to check against. The Diopter walls have not been counter bored on the inside either, so the walls are thick in that area to accept a thread. As I said... The hole is much smaller so that the customer could MILL a new hole at whatever angle they need and make it work. Sorry you are on your own on this one... just not cost effective to test / check 100% when 99% of the customers will never have the money to buy a SIG SANs target peep sight much less have the need to use it.

Fiber Optic Option:(Again NOT included with this set) The holes for the fiber optic option in the rear Diopter are also smaller than the original. I did this so that you could buy the sight without the fiber optic and drill the holes out to fit the Tritium Ampules / Tritium Inserts. Due to the short shelf life, cost and pain in the ass import regulations I have no intention of ever offering Tritium anything for sale. Check the forums for suppliers.

Above is a photo showing you the two options side by side (with or without fiber optic).

Materials of Construction:

The Rail, Diopter & Diopter Sled are 4000 series cast aluminum.

The SIG 552 SANs Style Non-Hooded Flip Front Sight is CNC Machined Steel.

The Windage adjustment wheel & knob and other small parts are steel.

Finish: The Rear Sight & Rail are painted to match SIG 556 Black Finish. The Rear Sight is made from special 4000 series aluminum alloy to allow it to flow more consistently into a mold. Unfortunately the non-aluminum alloys used (in particular copper and silica) make it impossible to anodize, so the rear sight and rail are painted like the originals were. The rear sight housing and rail are near 99% finished when they come out of the mold. We tried to retain many of the casting marks and even simulated some of the grind markings found on the original sight housings. I am not aiming for 100% perfection in a product as that is pointless and no cost effective. So if you have a safe queen that is worshipped rather than used... no MFI product is likely to live up to your standards.

At the front of the rail you will see a Swiss Style Cross and Shield. Additionally we have shaped the front of the rail to have a similar cut out that would normally be used for a scope mount, but in this case is strictly cosmetic. I spend a lot of time on the finer points of the design as it is critical to make any product as cool looking as possible. I hope you all approve.

Comes with: 3 – MFI SIG Top Rail Bolts and Allan Key

NOTE: Copying the original as closely as we did has it’s advantages and disadvantages. While we try to maintain the look and style of the original rear sight any deficiencies that exist in the original design will likely come through as well on the reproduction. A good case in point is the Windage Adjustment Knob. Originally designed to use a Swiss Franc Coin to adjust, even the original SANs sights get the paint chipped or the edges of the adjustment slot scratched or damaged in some manner. For this reason we recommend that you adjust the knob by hand (yes possible) to avoid damaging the finish of the knob. The next best option is to use a coin (dime) with thin tape on it. The coin is what was originally used as the slot is dished to receive the rounded edge of a coin and NOT the flat edge of a screw driver.

In this latest production we moved from a painted windage adjustment knob / screw to Parkerizing it and then cold bluing it for a chip free finish. Use of a screw driver or any sharp or incorrect size / shape tool can damage the slot.

MFI Front Non-Hooded SIG 552 / SG-553 SANs Style Sight: AVAILABLE

Here is a link for more photos, information, pricing to order separately and instructions on the installation of the front sight. Click on the "Instructions" tab:

Attention Quad Rail Owners: I have been informed by one Quad Rail owner that our Diopter rail does not fit plug and play with is 556P (Pistol Rail). The owner told me that it looks like he has to remove 0.0650" of either the MFI rail or the Quad rail to make it fit.

Sorry I never expected anyone with a quad rail to want one of these as this is a Retro Design. I designed this specifically to fit the Swiss SANs 551 or MFI 556P/2 Hand Guards and to be tight so as to eliminate some of the movement "slop" of the hand guard. I have tested the original SIG USA "SIG 556 Fish Gill" hand guard and the SIG USA Classic / SIG 556 / 551A1 hand guards and they fit fine as well.

So, Yes the MFI SIG 550 Style Diopter Sight & Rail is a hair longer than the stock SIG USA 556 rail. Again this will be a very tight fit for the 3 hand guards I mentioned. Going on is easy as you just press down, coming off is a little harder and in either case you can if you want undo the Diopter Rail (nothing falls out of the bottom like the SIG 556 rail thumb nail does) and reattach the rail. You will not lose zero on the iron sights as the tolerances of the 3 hole set up are very tight.


In accordance with the Joe Biden & Beto O’Rourke directive I personally as well my company no longer own(s) or possess any firearms or ammunition. This includes but is not limited to: Handguns, Pistols, Shotguns, Rifles, NFA items, Hog Legs, Fire Sticks, Smoke Poles and or Thunder Clubs.

All firearms that appear on our web site, regardless of what is written about them, are not owned by the company nor possessed by anyone associated with MFI and may even be CGI / PhotoShop.

Therefore regardless of any new firearms laws / taxes, no probable cause can EVER be assumed on any property (stationary or mobile) owed by myself or MFI.

AGAIN: We are 100% in compliance with any possible new “Biden / O’Rourke Public Safety Act” and therefore NO PROBABLE CAUSE could ever be assumed.

Lastly anyone arriving with a warrant of any kind will be assumed to be an IMPOSTER with intent on murdering us and will be treated as such without warning.

Those invading our territory may receive serious and even fatal wounds from rusty blades, clubs with bent nails, spear tips, arrows and or crossbow bolts.


This item is NOT RESTRICTED FOR DOMESTIC US SALES in any way and we offer DOMESTIC USA shipping to ANYONE. We ship to all 50 US States as well as all US Territories i.e. Guam & Puerto Rico. Sorry we can NOT ship to ANY APO address regardless of actual location.

This item is 100% RESTRICTED FOR EXPORT OUTSIDE THE USA. The US Department of State regulates / restricts this product and it is NOT EXPORTABLE outside the USA even to LE, Governments or Military without State Department approval.

This approval is AVAILABLE through MFI as we are an ITAR / Dept. of State Registrant with the Directorate of Defense and Trade Controls Office. We can obtain a US State Dept. Export License for you.

Please feel free to contact us if you have any questions on this issue.

Shipping Information

  • Item Requires Shipping
  • 1.1 lbs.
  • SHIPPING IS INCLUDED VIA USPS on orders over $82.00 Dollars AND OR If S&H is INCLUDED in the Title / Discription.

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