The first thing to note is that the magnification that you use for reading may not be the same for shooting. The reason for this is because, when you shoot, you hold your firearm out at arms length. Now think about how you would typically read a book...you hold it much closer. An arms length, when it comes readers, makes all the difference. 

1. Go to your local drug store and locate their reading glasses section. Bring a pencil along for testing purposes. 
2. If you already know what your reading glass magnification is, try on a pair of reading glasses at a magnification that is slightly weaker than your reading glasses.
3. Now, hold your pencil out at arms length. With the glasses on, focus on the tip of the pencil like you would your sights. If the tip of the pencil is clear, this would be the correct magnification. If it is not clear, try different strengths until you can see the tip of the pencil clearly.

BONUS TIP: Ways to customize your Top Focal^® glasses to improve accuracy

• Using the Top Focal Assorted Kit, wear both right and left Top Focal^® lenses. This will make your sights clear but target softly blurred. 
• Using the Top Focal Premiere Kit, wear a Top Focal^® lens on your dominant eye and a Chelan lens (no magnification) on your non-dominant eye. This will make the sights clear and the target unobstructed with both eyes open.
• Using the Top Focal Ultra Kit, wear a Top Focal^® lens on your dominant eye and a Denial lens (bottom bifocal) on your non-dominant eye. This will make the sights clear, the target clear, and reading clear when using both eyes