These shelves are SUPER in several ways - super easy to assemble; super strong will hold up to 1,000 lbs; super easy to roll on heavy the heavy duty wheels. I am really pleased with this purchase. For the record THESE SHELVES COME WITH BOTH LEVELING FEET AND HEAVY DUTY WHEELS. Each shelf has a rated capacity of 250lbs when the unit is on leveling feet for a total of 1,000lbs. When on wheels the rated capacity drops to 500lbs total.OK, assembly first. Read the instructions first. Life will be much easier if you do so. Choose an assembly area where you have plenty room on which to work. The first step is to screw either the leveling feet or the wheels into the four bottom pole sections then screw the four top pole sections to the partially assembled pole bottoms. There is a short threaded pipe already in the top pole section. Hand tighten this threaded pipe in the top section then carefully thread the bottom half of the pole to the top half. Next step is to take one shelf (they are all alike) and stand it up against something with its long axis on the floor.Each shelf rests on and is held in place by a two piece tapered plastic collar. These collars snap together around each of the four poles where you want the shelf to be so go ahead and snap the four collars (eight pieces) around the poles near the bottom. Then insert two of the poles through the bottom holes in the shelf up to where the collars are inside the holes. Next do the same thing for the two poles on top. Once you've done all four poles carefully lift the shelving unit and rest it on its wheels (in my case). The take a rubber mallet and tap each corner of this bottom shelf until all four corners are fully seated on the collars. Leave the shelves upright and repeat the shelf assembly for the two intermediate shelves. You can choose any vertical spacing you want for these two intermediate shelves. I wanted a taller space on the bottom, no problem. I took one sample item for the things that would be on the bottom shelf, on the second shelf and on the third shelf. From these items I gauged where to put the collars to hold shelf two and shelf three. The collars for the top shelf should always be at the top of the poles. Once again after snapping the collars together around the pole lower shelf two to the collars then tap in place with the rubber mallet. Repeat for shelf three and for the top shelf. It takes longer to write about this than it does to accomplish it.This whole assembly process took me less than ten minutes and was absolutely hassle free. Amazingly well engineered. One question I see about this unit is can the shelves be assembled upside down so that there is a retaining lip around the perimeter of each shelf. No, they can't be assembled like this. The mounting holes in the shelves are slightly conical to provide a snug fit over the collars which are also slightly conical. BTW, each half of these collars has an up arrow and TOP is molded in to the plastic at the top. One cannot assemble the collars incorrectly the way the two halves mate with each other. Just keep the arrows pointing up.I would buy these shelves again in a heartbeat or buy other shelves form this same manufacturer. So good luck and happy shelving to everyone!!!I'm a little old lady, and I was able to put these shelves together quite easily. It was sort of fun. I'm using the shelves to store office supplies.I have 2 of these shelving units in my home, one that is filled with indoor plants and one for kitchen appliances- both are very sturdy and do exactly what I need them to do. They were easy to put together and I would definitely buy more in the future if needed.First of all NSF standards what is that! It stands for National Sanitation Foundation. They ensure that the products they inspect promote food safety. Now that that is cleared up. These shelves are not the same as the big box store shelves that look just like them. These wire shelves are thicker and zinc coated (not chrome plated) which will peel over time or as it gets roughed up. I bought these to organize paint cans and other boxes for storage so the NSF rating is overkill for my usage. I would give a 4 1/2 star if amazon made that possible. These shelves are not sagging with multiple 1 gallon paint cans on them and the shelf unit looks great. why not 5 stars? The plastic shelf locks that keep the shelf in place are plastic. Some of them slipped while putting shelf in place. However, once in place, they are handling the weight load. I plan to buy at least another unit for more sh... stuff that i have to organize.Got this for my garden shed to keep pots and hoses for winter! It’s sturdy and worked perfectLove these shelves. Very durable and easy to assemble.Ordered a second one.I can't find the words to express how happy I am with this shelf. I was so afraid it would arrive damaged or with missing parts. This is a sturdy (but maybe not commercial quality) shelf. I'm a guy, so I didn't follow the directions for assembly. I live alone and had to figure out the best way for one person to do it. I laid out all of the part and then decided the best way to assemble it was on it's side. I put the wheels on last. Took less than 15 minutes and part of that was removing two wheels and moving them. I first put the wheels on like you would a cart with the locks at one end. I decided to move them so that the lock were on the "front". Did I mention how much I love these. I just ordered a second set. It sucks that Amazon started charging tax in my state. 5 bucks to the Governor...I bought this to use as boot rack in the hallway and it is perfect! The adjustable shelves make it easy to accommodate our boots and with a little DIY I was able to include shoes and sandals! It is good and sturdy so I don't have to worry about knocking it down or tipping it over and I threw a few hooks on there and now it holds my shopping bags too! Very happy with this productI was super impressed with these shelves. They are sturdy and super easy to put together. Although the adjustable feet look cheaply made they function perfectly. I'd highly recommend these just be sure to measure your space carefully before ordering a shelving unit.These are great but not as tall as the other model. In fact, there is exactly the same amount of shelf space in both the 5-tier narrower unit as this 4-tier wider unit. Have bought 2 as they fit exactly the floor space as planned.Product arrived before schedule. After getting by the installation of the first shelf the rest were a breeze. Very Sturdy and good looking.Holds everything I wanted it to hold. Really happy with purchase.Ordered one of these online because it was nearly 1/3 the price in stores. For a perfectly and was so easy to assemble. Holds a lot of weight. I ordered one more for myself a day two for a family member.