An oilless screw compressor incorporating water-cooled cooling units for cooling compressed air discharged from compressor bodies having a pair of male and female screw rotors which can be rotated in a contactless and oilless manner, the cooling units comprising a plate type heat-exchanger, and the amount of cooling water for the plate type heat-exchanger being adjustable. A protective cover includes an inner cover and an outer cover, and secured to the housing. The indicia comprising a card value series defined as a series of nine numerical attributes two thru ten and four face value attributes Jack, Queen, King, and Ace. Heart rate reserve values are derived from the actual heart rate along with patient age and rest heart rate. A gauge block rotatably supports the angle gauge.