wall portion 58 and a flange 60 the sidewall portion 56 is of substantially cylindrical configuration and it has an outer end 62 and a plurality of elongated circumferentially extending slots or air circulation openings 64 are formed in the sidewall portion 56 adjacent the outer end 62 thereof in this regard the air circulation openings 64 are positioned so that when the cap 44 is received over the bimetallic disc 42 with the disc 42 positioned adjacent the end wall 58 the slots 64 provide communication between the exterior of the cap 44 and the underside of the disc 42 the slots 64 are normally formed so that they extend around at least 50 of the circumference of the sidewall portion 56 and preferably so that they extend around at least 80 of the cylindrical sidewall portion 56 the end wall portion 58 extends substantially perpendicularly inwardly from the outer end 62 of the sidewall portion 56 and it has an enlarged central aperture 66 formed therein so that the end wall portion 58 has a substantially ring like configuration the flange 60 extends substantially perpendicularly outwardly from the lower end of the sidewall portion 56 and it includes a plurality of mounting holes 68 for mounting the thermostat 10 in a desired location when the cap and disc assembly 14 is assembled with the switching assembly 12 the cap 44 is received over the bimetallic disc 42 and the support disc 40 and secured to the housing 16 by suitable means such as by peening the.