Type Of Battery
The first thing you have to do is look into the type of battery they are using. After all, if the power supply is not proper, it will affect its performance. Button batteries are often considered as a better choice as compared to the AA batteries. But, you must keep in mind that button batteries are not readily available. AA batteries on the other hand are not only easily available everywhere but they are also less expensive.
The Option To Turn The Laser On And Off
When it comes to comparing different laser pointers, it is important for you to make sure that it provides you good control over switching the laser on and off. There are generally two options available in this regard. Where some products use a sliding switch, others use a push button. The push button seems to give you more control, but it is up to you to decide which type of option you are comfortable with.
Type Of Lens
There are two types of lenses that are generally used in these products to focus the laser plastic lens and glass lens. You should prefer to go for the one with glass lens because it strengthens the output of the beam. On the other hand, plastic lenses are very much likely to go cloudy over a period of time, which will obviously adversely affect the performance of the laser pointers.
While you are using a laser pointer, you must have some mechanism to eliminate the dangerous IR radiation. So, make sure that the product you are considering buying has an infrared filter for this purpose.
Last, but not the least, do not forget to check the warranty period that comes with these products. Obviously, you should go for the one that offers you a much longer warranty.
Remember, the beam of laser can be very dangerous if you aim it at someone's face because you may end up damaging his/her eyes. So, you have to be very careful about how you are going to use these green laser pointers.