Catspin is a T-Spin Double → Double → PC opener, invented by CATboardBETA and Missplaced (Itsgr82beeme) on June 8, 2021.

Having both an early O and J piece reduces the probability of this opener being possible significantly, and shouldn't be used in such cases.

Basic setup:

First bag

The O piece can be substituted for a J in the case that you get an early J and a late O:

PC:

There is only one 4-tall PC (11.7%):

J setup:

O setup (same probability):

Continuations when there is no PC:

It is not totally unlikely that your second bag will not give you the required I, T, and S (Or Z in mirrored) pieces early. During these scenarios, there are a few options on how you could proceed: