Instruction: Extract information from the supporting document to answer the given question.

Input:
Question: Does this work with the IMAC mid 2011  21.5 inch?
Document: I have an iMac Mid 2011 21.5 inch, I bought this memory because it fits the type my iMac uses, but it sucks because it seems like its not compatible or something because makes the iMac restart every 2 hours! !
My 21.5inch Mid 2011 iMac is now flying it originally had 8gb of ram and I wanted to do something special for it so I got the Apple Memory Module 8gb 1333mhz DDR3 (PC3-10600) - 2X4GB and it is now flying with speed at a total of 16GB of RAM!! !
I bought four pairs of these and they work fine in my small fleet of Mid-2011 2.3 and 2.5ghz i5 Mac minis. Not much you can say about RAM - either it works or it doesn't. This does. Quick shipping too. Thanks.
I received thisMemory for my 2010 iMac 21.5.. Memory was super easy to install, Just make sure you feel it click!.... Great product for the price! Computer responds a little faster and switching between apps is more responsive.. But if you want real performance add an SSD:)
Received it a bit earlier than expected, and well packed in memory delivery tray.Due to dusty slot in my Mac, need to spent some time for cleaning up...It is successfully fit and load normally after insertion. Upto now, my Mid 2011 iMac is well doing and running...However unlike PC, there are no significant performance changes or upgrade effects at all...At least it is up and running, I am pretty much happy about it...Cheers!! !
I bought this memory for MacBook Pro 13 inch late 2011. I installed it easily, the computer recognizes it properly and function correctly. This update is the best way to improve the computer performance. Note: Apple recommended just 8 GB. some people however put 16GB. I not recommended it; I think that is not necessary.
So i bought these RAMs from here and when i installed them they didnt work on my MACBOOK PRO (early 2011 version).. My MAC didnt turn on after i installed them..
Order this ram for a good deal and fast shipping. I installed it in 5 minutes and now my MacBook is running smooth!
I definitely want to purchase another 8GB and increase my system memory from the current 12 to 16GB! Make sure you pay attention to the variables. My iMac is a mid 2010. If you purchase "laptop" memory versus iMac or the ridiculous mid 2010 or winter 2012 ( for example ) it makes a difference. Found that out the hard way, thou purchasing thru Amazon and returning for full refund was not a problem! Hope this helps you.
This memory is 100% compatible with my iMac and costs about one tenth of what it would have costed to get my iMac upgraded at the Apple store. It took me about 5 minutes to install it.There are a two things you should know BEFORE purchasing this memory:1. Not all Macs use the same type of memory. It varies by the model of your machine and the date it was manufactured. Do your research first!2. Adding memory won't turn a donkey into a racehorse.
Answer: Yes, i have installed it actually on a mid 2011 21.5 inch iMac.