Here's Qmx's description of the family:
Five-inch Mama has extra-long, gray fur with a slight sheen. She carries 10 little ones that also sport long fur in a variety of colors: brown, dark gray and white. Each Mama comes in a special container that features Nursery Tips and is designed to keep it safe and out of reach of pesky Klingons.If I'm taking the term "carries" right, I think that means the baby tribbles can actually be put inside the mama, so you can re-create your own tribble birthing and infestation, as one tribble suddenly turns into eleven.
QMx are currently only taking sign-ups to get on a pre-order waiting list, but I'd expect this will come some time in the coming months.