Instruction: Given a question and the related document, and generate the answer to the question based on the information provided in the document.

Input:
Question: What is the purpose and/or advantage of the Double Layer Mechanical Stage?
Document: This is an outstanding instrument at a phenominal price! This is the second purchase I've made. It has added features like double layer mechanical stage and the binocular component for easier viewing. Get 'em while you can, folks!
The specific about this scope that led me to pick it out from others was the mechanical stage (don't get one with manual). I can't say enough, it's a real microscope.
We homeschool our 6 kids and they love this microscope. From the oldest ones doing biology and chemistry to the youngest not yet in school, it's just fun to use. I like that it seems to be well built and the mechanical stage is smooth and steady. It could take my kids through high school and possibly college.
I bought this for my sixth grader for Christmas to help generate more interest in science. Boy did it work! She absolutely loves this scope. It is solidly constructed and very easy for her to transport. The mechanical stage glides smoothly and the objectives are clear and powerful. We have not utilized the oil immersion objective yet but I have no doubt that it will work flawlessly. Excellent quality and value scope for the money! Don't hesitate if you're contemplating purchasing!
I was looking for an inexpensive starter microscope for my children. From looking around it was clear almost all the budget starter microscopes are made in China. The example I received offered decent views and comes with a good selection of eyepieces and oculars to get started with. The controls are good for a budget microscope, the mechanical stage and fine focus work well. The integrated LED light and dimmer give good views for typical bright field work your kids may have to do in high school.
If you're looking for a good microscope, then congratulations, you found it. This item was packaged very well, and shipped with everything in good order. It was easy to set up, and I'm very pleased with the quality. The images are very sharp and clear, with great resolution. The movable stage comes in very handy for getting a good look at everything on your slide, and being able to move and dim the light source really gives a big advantage to getting just the right view.
(2) The eyepiece diopter and interpupillary adjusts work well for adjusting the focus and spacing between eyes. The image in the stereo viewer is collimated for both eyes. . . no double images with misaligned optics that could give you blurred image or misaligned fields to give you headaches. The eyepieces are just a bit tight when fitting them into the viewing head assembly. Not a big problem in my opinion.
Each eyepiece spins for diopter adjustment, and the eyepieces slide apart for interpuppillary adjustment. Focus with one eye closed using the focus knobs, then switch eyes and focus that eye buy turning that eyepiece itself. Now open both eyes: both will be focused but you'll have double vision: slide the eyepieces further and closer apart. At some point the double vision goes away and in a snap you get a very wide-field view: a single view.
This microscope is a remarkable value. It's a robust piece of precision equipment. It's a treat to have a binocular microscope. The X/Y knobs for adjusting the position of the stage allows for smooth navigation across the slide. Great light source with dimmer and adjustable iris. Truly a fine instrument.
Easy to adjust, the stage is well designed and the unit is well made for any University or High School scope. It has a good feel to it and is not so large that you need a booster seat. The utube videos are something necessary for the optimal adjustment process. Not sure who wrote the paper instructions. They tried. The vid is better.
Answer: The double layer mechanical stage actually means the stage will give movement of the slide to both horizontal and longitudinal directions.