Instruction: Answer the given question by extracting information from the supporting document.

Input:
Question: Will it fit canon t3i?
Document: and if not, you have the opportunity on the spot to make corrections. Glad I took that class if only to discover this invaluable tool. Just for reference, I have a Canon Rebel T3i camera.
Have taken several photography classes and the teachers all have one of these loupes. It is especially helpful outside to actually see if the picture you think you took has turned out. Frequently I just can't clearly see the 3 in display screen on my Canon T3i and my bifocals don't help. I can adjust the loupe and see just fine without my glasses. So glad I finally bought it
I am totally in love with my Hoodman HoodLoupe 3.0 Display Magnifying Loupe for my Canon 50D. It is easy to use; it is easy to carry, easy to pack in my camera bag, and easy to focus. I give this item a very big 5 STARS!
makes viewing your pictures on your lcd screen so much easier to make sure they are in focus. It beats having to keep zooming in on the screen and moving things around.
You all know how difficult it is when you are taking pictures in daylight... your LCD monitor on your camera has too much glare to tell if the pictures is in focus, or the lighting is correct, ...  Well the Hoodloupe solves that problem. What a difference!My only complaint is that the case only has a belt loop holder and I wish it had something to easily attache it to a camera bag.
When you need to rethink your photo this is the ticket to do so. It is useful in sunlight because it shades the screen as well.Would recommend.
To check for those errors many cameras permit magnification of the LCD display to 100%. This means the pixels in the magnified portion of the image can be displayed on the LCD to correspond 1:1 with the pixels in the full size image stored in the camera. This permits the photographer to check, for example, whether the eyes of the subject are sharp and in focus, and if not, allows the shot to be re-taken immediately.
This is replacing a my lost Hoodman. I liked the one I lost so it goes without saying that I like it's replacement.
This is one of those items that deserves 6 or 7 stars! What a genius idea. I recently took an outdoor photography class and the instructor allowed me to borrow his loupe. At the end of the class I was reluctant to give it up! The one I was using was the non-magnifying type but I decided with my eyesight a little bit of magnification would be helpful. So glad I made that decision.
This is obvously a good attachment for some cameras, but for our small digital, it seems to be awkward to attach. We will use it to the best advantage in direct sunlight, however, so we can see the images we are trying to photograph.
Answer: Yes it will fit 3" LCD screens.