Most are metal—usually steel or iron—often with plastic or PE coatings on the metal tubes; some planter panels are made from PP plastic.
Some planter-with-trellis sets include a self-watering reservoir or siphon system plus drainage holes. This combination reduces how often you need to water while helping prevent waterlogging.
Common extras include lockable wheels for mobility, self-watering reservoirs and drainage holes, zip ties and gloves for setup, stainless-steel hardware, decorative finials, and floral support bands.
Many feature protective finishes such as powder coating or plastic/PE coatings and are marketed as weatherproof, weather-resistant, or rustproof; some also include stainless-steel hardware.
They’re designed for climbing plants and vines—commonly roses, clematis, ivy, and jasmine—and for vining edibles such as tomatoes, cucumbers, peas, beans, and morning glories.
Raised-bed sets often offer adjustable trellis heights—examples show two height settings (for example, about 71" and 52") and adjustable supporting rings.