From the Original Author:
OPERATION: The speed loader is placed on top of the magazine, and pressed downwards (see figures). A small boss depresses the top round in the magazine and in turn compresses the magazine spring. Another round is then loaded, from the front, and pressed backward against the boss. The speed loader is then lifted slightly so the new round can be fully seated. This process is repeated until the magazine is fully loaded.
CAUTION: Firearms, ammunition, and magazines should only be handled by trained adults. This design is provided "as is" without any warranty.