The relevant production range for St Louis Cards, Inc. is between 150,000 units and 200,000 units per month. If the company produces more than 200,000 units per month,. O the fixed costs will remain the same, but the variable cost per unit may change Oboth the fixed costs and the variable cost per unit may change the fixed costs and the variable cost per unit will not change the fixed costs may change, but the variable cost per unit will remain the same