and which is available from medical graphics corporation of st paul minn as its part no 541115 pneumotach mouthpiece turning next to fig2 and 3 the mask 10 is seen to comprise first and second mask segments 26 and 28 each formed as a lamination of outer layers of spandex fabric 20 and an inner layer of synthetic foam rubber 18 each of the segments 26 and 28 is cut in a pattern to define a convex curve 30 of a predetermined radius of curvature at a first end 32 thereof a concave curve 34 along a lower edge 35 thereof that joins the convex curve 30 to a generally trapezoidal shaped area 36 proximate a second end 38 thereof the pattern further includes another concave curve 40 along an upper edge 42 that joins the trapezoidal shape area 36 to the convex curve 30 the mask segments 26 and 28 are secured together preferably by stitching along their respective convex curved first ends 32 thus forming symmetrical first and second mask halves velcro u00ae hook and loop fastening pads 44 and 46 fig3 are sewn glued or otherwise affixed in the generally trapezoidal shaped areas 36 of the two joined mask segments the hook and loop fastening pads formed in the trapezoidal areas of the first and second mask segments are adapted to be joined behind the head of the wearer and.