I'm looking to buy a powerful Laser Pointer, what should I be looking for

I like the green Laser Pointers, however, the come with all different numbers, such as 1 mW, 5 mW, 10 mW, ect. and 635 mw, 532 mw, ect.

However, which are the best numbers to look for when wanting a powerful Laser Pointer and one that travels far.

Yeah mW is how powerful.
Look at different powered lasers on youtube (1mW, 5mW etc.) to get an idea of how powerful they are.

e.g. 525 nanometers = the frequency = colour.

Green always appears brightest.

nm means nanometers, and that's the color of the laser. mW means milliWatt, and that's the energy rating of the laser. Higher is better.