To answer the O/P's question, yes that is a 30 amp RV to 15 amp outlet connector
and
To answer the question you did not ask: Yes that is a 50 amp Marinco INLET (plug) that matches the outlet on your shore cord
So you need (Already answerd) a 50 amp RV to 30 amp adapter to use that puck adapter.
As to running one A/C on 20 amps.. Done it many times.. In fact on 15 amps odds are good you can run ONE of the following, JUST ONE
Microwave, Air Conditioner, Water heater, Converter if batteries are hungry
(So plug in for an hour or two to let the batteries charge then turn on one other thing)
On 20 amp you can add the fridge to that list.
One Television will likely work as well but multiple and/or computers may put you over.
It is a numbers game, if you know the numbers it works.
