It is if the ball is about the size of a softball maybe slightly bigger and the pins are more straight up and down with a less hour glass shape.
Took the time to try out the Sock I threw together recently. I didn't spend the night, but had a couple of afternoon naps very comfortably - outside temp was 32-33 and inside ranged from 44-47. I used a 3/4 underquilt with 9oz 800fill, along with a thin Thermarest under me. on top I had my 20 degree bag. I bit of overkill for the temps, but it was a good first test.
===> Happy Thanksgiving, NEHHA! May it be a good day for all!
Thanks! you too, and to all as well.
Happy Turkey Day to NEHHA and all of HF!