If you are talking about the safety model Rami, the green dots are glow in the dark paint. When exposed to light they "charge up" and glow for a short time.
You can re-fill the dots with another type and/or color of choice. Not too many choices for sights on these models. Big dot sights are one and there are two night sights, Trijicon and Mepro Sights. Most people don't seem to care much for the Mepros.
Rear sight is pretty easy to replace. Front sight is a challenge to get out (it was at least for me).
I tried the Trijicons from CZ and they were better than the stock sight but ended up milling for an RDS.
