The first cage is the 2 level pink apartment one. If I knew there's a 3 level one I'll definitely got that one, think it's pet's home brand. not clear.
Can't really get any expansion like towers, maze, etc that can connect to the cage.
Then last Saturday I found the yellow one 1 level and has the same tube connection. Bought without second thought. I like it because there's an attached globe in the top and can take it off for the running ball on the floor.