To understand the weight of Imperial Armour Volume 1 Second Edition , one must first understand the context of its creation. Forge World, a subsidiary of Games Workshop, began producing highly detailed resin models for the "heavy hitters" of the 40k universe—Super-heavy tanks, Titans, and specialized aircraft. These models were too large and complex for standard plastic production at the time.
The PDF is a rules library for models that are now either out of production or incredibly rare: Imperial Armour Volume 1 Second Edition Pdf