"After a lot of research, I bought this cage and am very pleased with it. The nearest equivalent, from Martins Cages, is quite a bit more expensive.
PRO:
Sturdy IF put together properly. If it feels rickety, you've missed something.
Powder coated. Large enough doors. Good bar spacing for young rats. Room for 2 large or 3-4 smaller rats. Room for 11- or 12-inch wheel. Good ventilation. No chewable plastic parts!
MINOR CONS:
May not lock firmly into base - to move the whole cage, lift it from the bottom rather than by the handles.
Must be lifted off base to clean. (If you're getting your hands dirty doing this, you aren't cleaning often enough or you should consider another type of litter or liner.) Handles make this fairly easy.
Shelves are wire that could cause foot problems. It's easy to make carpets for all or part of the shelves, using plastic embroidery canvas or even old towels/clothes. I recommend cheap wooden bird ladders (Petco has these) to replace the ramps for foot safety. Some rats have no problems with wire, especially if it is kept CLEAN.
Shelves may be movable by very ambitious rats. Consider adding wire ties in a couple of spots.
Check carefully - mine had a sharp wire exposed on one shelf. It bent flat with pliers.
Overall, this is a great deal on a spacious cage."