The last time I recharged my R12 system, The top of the cans were just like cans for spray paint but without the plastic nozzle. The charging hose connects to the inner rim, the charge valve screws down into the hole in the middle of the can and voilá.

I just now bought some new cans of R12, but the center part has a thin metal cover. Is this cover supposed to be taken off, or is it soft enough for the valve of the charge hose to penetrate when attaching the hose?

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