Refill methods vary by design. Common approaches are sliding a new box in through an open-bottom cover, using a slide-out bottom for easy replacement, or removing a decorative top (for example, a bamboo lid) to swap in a new box.
Look for rust-resistant or rustproof finishes and matte black chrome coatings. Product descriptions may also note scratch-resistant or waterproof treatments intended for humid bathroom environments.
Stability features include a weighted or heavy base and anti-slip/non-slip pads. Several product descriptions highlight a weighted bottom to prevent tipping and slipping.