original green churchill swim-fins swimfins flippers UDT/Seal, bodyboarding

Description

This a vintage pair of Churchill Swim Fins.   These are the type of swim-fins used by UDT teams in WW2 and he predecessors to the Churchill fins still worn by bodyboarders around the world.
The date is presently unknown but the latest these are from is the 1970s.  The patent listed on them is 1940-1960 with a reissue, so I assume they are post 1960.
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Sizing - Med Large in modern fins is US 9 - 10.5, not certain about their time period.
Condition:
The rubber these are made from is much softer than the rubber than has been used since the mid-80s and is missing a lot of the stiffness.
These fins are not in a condition for use and are as a collector's item (they are in better condition than a lot I have seen after a few years of use - but would still advise against it).
These fins are experiencing some drying out (heelstraps and the curled  tip of the right fin).   There is no tears at the end of the toe pockets.
Writing visible from the fins:
Churchill
PO BOX 1456
Gardenia California
Reg U.S. PAT OFF
RE-ISSUE D-124.013
U.S. PAT NO. 2,099,973
23,005  2,321,082
Size  - MED LARGE