SA NAVY Gymnasium Cap Badge

[Milmed]

Hi,
A recent aquisition is the cap badge worn by the Navy Gymnasium in the 1950's. The example comes sans balck backing and I would like to know what the backing should look like. If anyone has one of these and could post some clear pictures It would be appreciated.

Second picture is of the shoulder title/arc worn by the Gymnasium on the black uniform. These also came in blue on white for the white uniform.

Third picture of an unknown blue on white naval title. I have anouther in red on black. Any assistance to a positive ID please.

Regards
Steven