Common materials include fabrics such as polyester or 600D Oxford, PVC-coated components, metal/steel frame elements, and plastic frame parts.
Many backpacks and soft carriers include extendable panels that increase interior width or headroom. Example expanded dimensions include 16.14" L × 25.19" W × 15.75" H; common non-expanded measurements noted are about 12.5 × 10.2 × 16.3 inches or 16.1 × 13 × 15.7 inches.
Carrying styles include backpack and front/chest sling carry, rolling carriers with telescopic handles, shoulder carry, and hand-held options. Several products offer multiple modes so a single carrier can be used in different ways.
Most expandable carriers use multiple breathable mesh panels or windows on the sides and top. Some models also offer a top viewing panel or a zip-up mesh window for extra headroom and visibility.
Common safety features include interior safety straps or buckles, anti-escape buckles, and self-locking zippers to help prevent escapes.