When sourcing silage pit covers, the most critical factor is the Oxygen Transmission Rate (OTR). High-quality covers should feature oxygen barrier technology (often using EVOH layers) to minimize spoilage. Additionally, ensure the material is UV-stabilized to withstand at least 12 to 24 months of direct sunlight exposure. The thickness typically ranges from 125 to 200 microns (5 to 8 mil); however, for modern bunker silos, a dual-layer system (a thin 40-micron vacuum film combined with a heavy-duty UV cover) is the industry gold standard for maximizing nutrient retention.