Buyers must prioritize the chemical form of copper, typically categorized into Copper Sulfate (Pentahydrate), Chelated Copper (EDTA/EDDHA), and Copper Oxychloride. Chelated versions offer superior stability and absorption in alkaline soils. Ensure the purity level is clearly stated, with standard agricultural grades usually requiring 98% or higher purity for sulfates. Additionally, check the solubility rate; for fertigation or foliar spray, the product must be 100% water-soluble to prevent clogging irrigation systems.