Lasers being sold on ebay that are over 5mW are very unsafe! Green lasers are diode pumped solid state lasers, or DPPS lasers. These lasers work by pumping a crystal full of Infared Light, which is 808nm and is INVISIBLE by useing  a Infared laser diode, in most green lasers this diode is ususlly 200mW! the crystal then converts some of the IR light into green, or 532nm light. not all of the IR light is converted into green however, it is uaually a very low percentage, all of the excess IR light goes through the crystal. After the crystal on 5mW units there is a Infared filter. This filter blocks out all of the excess Infared light that is not converted into green light.

Now the problem with the 10mW, 20mW, 50mW, 80mW and any higher powered laser sold on ebay...

Many sellers buy cheap 5mW green lasers form ebay and take the IR filter out. this is a problem because all of the wasted IR light is now being released whenever the laser is on. This IR light is not colminated, meaning it is not a small dot, like the green light, and since it is IR, many things that dont look reflective do infact reflect IR light. Now i dont know about you, but i dont want more than 50mW of light getting into my eyes, that is more than enough to blind you! The worst part is you cannot see this light and you will not know when you are looking at this light untill you are blind!

Also, the green beam of the "high powered" lasers sold on ebay are not any brighter than a 5mW green, they just cost more!

When it seems to good to be true it usually is!