2X NOS Replacement Watch Crystals for Benrus Military DTU-2A/P MIL-W-3818B 

Only two crystals are included.  No Watch! 

It is New Old Stock after market crystal.  It is made of acrylic plastic, similar to the original.

The watch shown has one of these crystals installed.  I show multiple pictures of the watch to give you an idea of how this crystal looks on the watch and to be clear on the watch case number for application.

I tried several brands of crystals with no, or limited success before I found these.  This had the nearest to original look (and fit) I could find.

A couple crystals I tried had too tall of a look and just didn't look right.  One crystal that was mentioned in a Google search as a good fit had a tension ring which hits the lume markers making dust in the watch, I do not like using any crystal with a tension ring on this model watch.

I show the new crystal side by side with the old original crystal.  You can quickly tell which is which by the large crack in the original.

This crystal must be installed using a watch crystal vise or installation tool. "The claw!"  It compresses the crystal making it small enough to push into the case.  I show how the crystal is inserted into the vise.  Not all the way to the top edge, give enough edge to be inserted into the case.  Tighten it up just enough.  Snug plus.  It's king of a feel thing.  To tight and you could damage or crack the crystal, to loose and it won't snap in (That is why I include two in the listing).  Start too loose and work up to just right!  You can't make it work with out one of these tools, (They are not very expensive and work on a large range of sizes.)

Because this is a one piece case (The back does not come off), and it does not use a bezel crystal retention ring, the simple claw is the best option.  Not a crystal press.

There are a number of like model military watches (They look about the same but have different numbers).  Some take the same crystal, and some do not.  I have not tried this crystal in any other models to know what else they may work in.

This is a link to a thread in the Military Watch Resource Forum where they are discussing the crystals required for variants of this type of watch.  If you have the exact number mentioned in this listing, this crystal will fit, if you have a variation of the number listed, please check out this link.  

http://www.mwrforum.net/forums/showthread.php?39679-Crystal-size-type-for-MIL-W-46374

Email me with questions. 

Of further note:  An eBay member messaged me with this - 

I saw in forum that MIL-W-3818B and GG-W-113 and 113A use the same lens. all the 31.1mm ledge type. Maybe that will help you with knowing the other models this lens should fit.

I have not personally tried this crystal in a GG-W-113 so I include this info as a possible solution.  Some one, please email me if this is not the case.