There are 3 types of green diodes around; 510, 515, 520nm. They all can vary a bit, depending on heat.
Diodes are more stable, and reliable than are DPSS lasers. Unless you paid well over $100 for your keychain laser, it's a DPSS.
My 520nm SSW runs @ 115mW peak with a G-2 lens on it, and it is...