A cap frame is the device that a cap is clamped to securely so that it can be embroidered. The cap frame is then attached to the Cap pantograph.
There are two types of cap frames used in embroidery. Nowadays, the standard cap frame is the 270 Cap System which allows operators to embroidery on 270 degree area of the cap. This is basically ear to ear. The older version is know as the Standard Cap Frame. The older version only embroiders on the front of the cap (not the sides).
In order to use either the 270 or the standard cap frame, the embroidery machine needs to have the ability to embroider on caps with all the cap driver equipment