Laundry bags as stabilizer?

Enid of “Designs by Enid” writes about the use of laundry bags as wash away stabilizer.  What is a laundry bag?  Enid is in Africa, I am in Texas.  Is there something comparable here?  Anyone know?

According to Enid, these are no longer available, but perhaps someone else has more information?

Margaret Hardwick-Smith

Secrets of Embroidery