These listings use a few common materials: HDPE/polyethylene plastic, galvanized metal, and wood or MDF, depending on the model.
Heights vary by style: lower freestanding gates and playpens are listed around 23.5–24 inches and 32 inches, while extra-tall metal gates appear at about 59 inches and 67.5 inches.
Many models are designed for portability: plastic playpens use removable panels and tool‑free connectors, and several wood or freestanding gates fold or ship fully assembled for compact storage or travel.
Several products include lockable access: plastic playpens may have lockable door rails, and extra‑tall metal gates typically offer a large, lockable main door (swinging both ways) plus a lockable low door for very small pets.
Indoor stability is provided by suction cups or anti‑skid pads; for outdoor use some playpens include ground stakes or other anchoring options.
Safety features include rounded corners on plastic playpens, closely spaced bars on wood gates, and dense metal tube spacing (about 1.37 inches) plus extra vertical bars on metal gates to minimize gaps.