The blitzkreig sights use a small tritium vial and it is pretty far below the top of the chevron. I found on my M2 my eyes had trouble picking up the top of the post quickly. On my 14" 590 it wasn't an issue, but that one doesn'thave tritium just the luminescent green paint. Being quite a bit closer to my eye is the biggest difference. I went with an XS standard dot orange/tritium on the M2 and like it a lot more. Its the same width as the oem front post but the rounded top makes it easier to place the target at TDC. The orange is very visible and the tritium is easy to pick up in low light. Not that tritium is that useful but if you're paying for it its nice if it works properly.