Interesting... It's not a Bomar though...
Notice, back by the blade, there is no adjustment screw for windage. Normally, the captive end show's on the port (left) side, and here, it's solid or flush. Also, the rear blade appears to be pretty verticle, and not angle to the rear for glare reduction.
It may be a clone, something possible where the Bomar leaf is set into a special mount, but regardless, the blending of the mount to round the leading edge is a nice tough.
Still, the newer Low Mount versions of the Bomar's, and even Wilson's adjustable sight seem to sit much lower, and have less exposed area, providing a slightly cleaner look, rather than the "tumor" approach.