5.6 Quality Performance. Supplier shall make commercially reasonable efforts to achieve and maintain a defect level (parts per million or “PPM”) of zero (0) with respect to its manufacture of the Products. At a minimum, Supplier shall maintain a defect level at or below the performance levels specified in the SQM for a “Preferred”/“Approved” level supplier in the relevant supplier category, as measured by and for each Site. If during any period Supplier fails to meet applicable performance requirements, Purchaser may by written notice suspend any obligation it may have to purchase Product affected by the quality escape.