I know this gets confusing because its different all over the internet but according to Ring Sight.
From Ring Sights:
HC-14-62 - White Reticle Ring Sight with plastic housing.
MC-10-80 - Black Reticle Ring Sight with metal housing.
Wiki has it listed the other way around. Personally I am a bit confused myself. Maybe someone can ask FN in the next Q&A for a difinative answer.
---------------
RING SIGHT HC-14-62
FN chose our HC type with a circular aperture of 14mm diameter for their P90 sight. The HC design has a dual reticle - rings and a dot for day, open T for night. The open T doesnot obscure the target which may be difficult to discern if the reticle overlays it.Its height is greater, for a given aperture, than the LC type but this can easily be fitted intothe space between the barrel axis and the sight line. On the P90 the optic housing is plastic and the interface of the housing with the gun is by two zeroing screws.The optic can be put into other housings such as one with a laser pointer beneath it,complete with the laser battery, on a zeroing mount with range settings, the whole on adovetail interface for the British 5.56mm rifle.
RING SIGHT MC-10-80
The MC-10-80 is specifically designed for the FN Herstal P90. The sight is a unit power telescopic sight with a black graticule for day use and a open T for night use lit by a red tritium light source. Being NVG compatible it is ideally suited to 24 hour operations.
--------------
Here is the info direct from Ring Sight:
http://64.233.167.104/search?q=cach...s/13733.PDF+HC-14-62&hl=en&ct=clnk&cd=5&gl=us
http://www.ringsights.com
This one shows the (rear light collector) "T-bar" lit up with a flashlight.
This is the front light collector of the White Ring Sight.
This is the rear light collector of the White Ring Sight (A). notice the white tritium bar at the bottom of the well (B).
This is the bottom view of the White Ring Sight. You can see the white tritium bar imbedded in the clear gel caseing.
Here is a great web site that has lots of info on the PS90.
Overview (size, weight etc.)
Mechanical Characteristics
internal and external parts descriptions
ballistics charts
http://en.wikipedia.org/wiki/FN_PS90 :shock:
Click on this link to get a detailed description of how the white ring sight works. It even has a visual.
http://www.remtek.com/arms/fn/p90/sights/index.htm
Check this link out. It also has info on the 2 Ring Sights.
http://www.ringsights.com/Products/sights/SightsDesc/MC-10-80.htm
:?