Anyone know about these?

Looks familiar but OMG
I cant think what it is?

They're fairly common and come in a variety of gorgeous mutations. You can see pictures at http://beautyofbirds.com/redrumpedmutations.html

I'm familiar with grass parakeets, but not red rumps specifically.

With most of the grass keets, I'm familiar with the species name and can recognize that a bird is a grass keet when I see one. But I have to get on the internet and look them up to connect the right name with the right bird.

All I know is that they don't go well with tiels but you won't have this problem. Sorry for not being very useful

There super cute