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

Input:
Question: Is the 5CS2-2122-CR-21" unit 21" wide x 18" high and how tight is the width?  (can the shelf slide out of an 20" opening?)
Document: I've ordered 7 of these for my kitchen cabinets and am ordering 5 more for my pantry. I'm actually looking into using them for my powder room and bathrooms. Have to do some measuring. They are quite sturdy and very easy to install. Measure carefully to make sure that the baskets will slide out without touching the sides of the door opening. I highly recommend this item. Shipping took forever for the double basket ones...3-4 weeks. The single sliding basket came in within a week.
Now the bottom drawers are binding when they slide in, and out. I think this will make for an early failure in a couple years or so. I would have sent the whole works back; but in our case, they will get limited use,under a new window seat, and my wife didn't want to wait for replacements.
It's too tight now, but it's doable and the drawer stays in. Maybe we just got a fluke bad one. Seems well-made otherwise, so if I needed to, I'd probably try another one of their products.
previous cabinet shelf broke, so ordered this to replace.This has been fantastic would highly recommend.Was also fairly easy to install just followed the instructions.
The shelf I ordered was just as advertised, extremely heavy duty.It was easy to install and fit perfectly.We loaded it with heavy pots and pans-it slides in and out easily-well made product. I will get more of these when we re-do our kitchen cabinets.
I really didnt know what to expect but when it was installed I can't believe I was all these years without it. I only had half a shelf on the top before and now with the double pull-out I have more space for storage. You don't have to search for what's in your cupboard just pull the basket and it's right there. This product is sturdy and very well made. You won't regret buying it.
I've installed 3 of the Rev-A-Shelf double pull-out chrome wire baskets in my kitchen. They are very good quality, and easy to install if you have even a modest knack for such things... requires only a screwdriver (or better, a cordless driver). Watch the dimensions carefully.Installation instructions are adequate.Note:  these are about convenience, and not about storage efficiency... i.e.
This product was even better then what I thought it would be. Very well built and sturdy beyond belief. Worth every penny. In fact I ordered two more! !
This product looks and feels great- very sturdy and well made. There was a little design flaw, though.I assembled the frame work and before I screwed it into the cabinet, I wanted to make sure it all fit, so I tried putting the drawers in. I put the bottom drawer in, and it worked fine. I put the top drawer in and the sliding rails were too far apart. There's nothing in them that actually interlock with the grooves on the drawer to keep the drawer in there.
The pull out shelves are very well built and sturdy. They fit beautifully in the pantry and make it so easy to find things now. I would (and have) recommended this to my Mom!
Answer: The cabinets I installed them in are 20 1/2" opening and there is about 1/4" on one side to play with. Make sure the cabinet door does not interfere with the open space.