There are three things that contribute greatly to the effectiveness of reading glasses. They are; the amount of light available, the reading glasses strength, and the focal length (the distance to the point of desired focus). Since a stronger strength is better closer to you, and a weaker strength is better further away, were going to look at how to buy reading glasses at different strengths, for different tasks, so you can see what strength reading glasses might help you with tasks that vary from your everyday use.
0.5 reading glasses, or even reading glasses at 0.75, might seem to be strengths that could be avoided simply by moving the object being focused on further away, but what if your everyday strength reading glasses is 1.00, you used a computer monitor that was 30 inches away, and you used it for hours at a time? A 4.00 may seem like a strength suited only for bullies burning ants on a sunny day, but if you're regular strength is 2.00 and you are tying fishing flies or working on detailed fine jewelry, tasks that occur much closer to your face, it may be perfect.
What strength reading glasses are right for a specific task at a different distance than your everyday use? Gauge that as you would your everyday strength, but at the distance the task occurs. Hold something relevant at that distance and see what strength is initially most comfortable. See what strength feels most natural without your eyes having to work to focus.
The free shipping on two or more pairs of Ultimate Reading Glasses applies to different strengths as well as different colors, so take advantage of that if you need more than one strength to make your life more effective, and more comfortable!