Rear Sight Rails

Steve at The Firearm Blog has a post up about Strike Industries's rear sight rail.  These are similar to the Iron Dot style mounts that Midwest Industries and Attero Arms currently produce, but they differ in that they have a more universal Weaver/Picatinny rail and do not co-witness.  If you are interested, Strike Industries looks to be the most affordable.  However, Samson makes one with an under rail tunnel for the rear sight that usable with the optic on but it is pricey.  The Scout Scopes mount is lower and also offers a rear sight for use when the optic is removed.  Polytech also makes/made one that is available at a few places but I'm not sure of it's current production status due to the Chinese import ban here.  It looks not to have a rear sight option.