This is a Hi-Viz Sight known as the LiteWave H3, model MPN521.
HIVIZ(R) LiteWave H3 sight combines Tritium with our LitePipes technology for day/night performance with 24 hour illumination. Front and rear sight are green. 12 year Tritium warranty. Fits M&P full-size and compact in all calibers. Does not fit CORE" M&P 22 or M&P long slide models.
Features:
Green tritium front with orange ring
Green rear
Sight visibility in all light conditions
Factory sight heights
