Raised-Bed Kits have DuraMeshTM galvanized wire liners, which promote optimum air circulation and drainage while preventing pests from burrowing under the plants. The kits consist of composite lumber (which will reportedly not rot, crack, split, or splinter) and temperature-resistant stacking joints. All 4 feet wide, they come 8-, 16-, or 24 feet long and single-, double-, or triple-tiered.