There have been numerous books which describe the design and use of the gun motor carriages fielded by the U. S. Army's Tank Destroyer branch in WWII. This book is unparalleled in bringing to light the development process of these tank destroyers and the various prototypes which the Army specified, designed, built, and tested. The descriptions have been compiled from the original Ordnance Branch records; other sources include the proving ground reports and the reports of various service boards. Many of the photographs included in this book are published here for the first time. Can Openers is an incomparable resource for a detailed history of the anti-tank developments of the U. S. Army during WWII.