Bests & Worsts Reviews from Amazon

I've used metal shelves like this from other brands such as Alera, Whitmor, Seville and they all work great (and basically in the exact same way). When I saw these metal shelves by AmazonBasics at a cheaper price and with such great reviews, I figured it was worth a shot. Dude.. these suck. With just a little pressure, shelf just slides down the pole. After checking everything and taking it apart I saw that the plastic ridges in the sleeves had totally rubbed off. So I got another pair, and again, with the slightest pressure, the shelf just slid down. The same thing happened, the ridges in the plastic sleeves had totally rubbed off. This happened on 4 sets of the plastic sleeves. I'm guessing they used some cheap, less durable plastic. If you look at the 2nd picture, you can see that the plastic ridges that are supposed to catch onto the metal pole are basically gone. There's no way these would support 250 pounds per shelf. Maybe I just got a dud batch of plastic sleeves?