From eight chain thru or parallel wave formation: All pass thru then those facing out do a partner trade while those in the center take the next call. Finishes in double pass thru formation. (An alternative to Dive Thru that works from waves where Dive Thru doesn't).
Jack Murtha 1966
This definition is from The Handbook of Modern Square Dancing by Jay King.
It is provided here for informational and educational purposes only.