Kraljic (1983) considered two variables: profit impact and supply risk. The profit impact of a given supply item can be defined in terms of the volume purchased, the percentage of total purchase cost or the impact on product quality or business growth. Supply risk is assessed in terms of the availability and number of suppliers, competitive demand, make-or-buy opportunities, storage risks and substitution possibilities. Based on these two variables, materials or components can be divided into four supply categories: (1) non-critical items (supply risk: low; profit impact: low), (2) leverage items, (supply risk: low; profit impact: high), (3) bottleneck items (supply risk: high; profit impact: low), and (4) strategic items (supply risk: high; profit impact: high). Each category requires a specific supplier strategy.