I haven't seen anything here about these and just came across them on bookface. It looks like a set of sights similar to his all black, steel sights but with a front tritium vial placed in the lower portion of the blade. Seems to be a very interesting design, never considered that. Mr. Defoor seems to be an innovative gent, I'd be interested to tryout a pair.
Ameriglo GL-514
(Photo from the bookface post)