Changeable parts and variant models are often utilized throughout the line, offering the collector a wide variety of display abilities. The collectible figures use PVC (with some ABS plastic) for construction materials, and a recently introduced expansion to the line use metal in the skeleton of the figure. Gundam FIX figures are designed to be true to Hajime Katoki's vision, and as such often adopt design elements and styling found throughout his artwork. The Fix series caters to Gundam fans who enjoy the scale, possibility and durability of the MSiA line, but seek the extensive details and variations that can often only be found in the Master Grade Gundam model-kits.