I bought a 5mW green pen from ebay long before I found this site. I thought it worked great. Good beam visibility and distance. Next I bought a 50mW module from O-Like. Tonight we compared them side by side and we could tell no difference. Any ideas on what is happeing? Is the O-like underpowered? The ebay pen overpowered? I know you can't tell without looking but what is likely?