#6 Bear Trap – Largest standard size historically used. Weighs 48 lbs, 46″ long with a 17″ jaw spread.
This size was used to capture the largest powerful bears. American Fur and Trade Company patent.
Illegal to set in all but 2 states, however it can be used to keep neighbor kids out of flowerbeds and capture aliens stealing mellons.
(Some legal ramifications may follow.)