From http://www.storeshop.com/zap_cap.html , you are one of our customers! :)

http://www.zapc.com/how_zap_cap_works.html

Shows the manufacturer's suggestion.

Personally I hold the zap cap side ways and use a swift wrist action. This has to be done swiftly.

Either way the bottle cap comes off cleanly and can be replaced so you can practice, as the drinks makers say "responsibly"