referring to the drawings in greater detail and by reference characters thereto , there is illustrated in fig1 a a roof ventilator according to one embodiment of the present invention and which roof ventilator is generally designated by reference numeral 10 . initially , reference will be had to fig6 illustrating roof ventilator 10 in an exploded view . for purposes of explanation , applicant will refer to first and second sides , a front , and a rear . these terms are used merely for clarity of description and the invention is not limited to this precise arrangement as different configurations are possible . roof ventilator 10 includes a base generally designated by reference numeral 12 and which base 12 has an upwardly extending pair of side walls 14 , 16 , a rear wall 18 , and a front wall 20 . located on side walls 14 , 16 are locking lugs 22 . extending outwardly from side walls 14 , 16 , rear wall 18 and front wall 20 is a base flange 24 for securing the roof ventilator to the roof . to this end , base flange 24 is provided with nailing apertures 29 to receive nails 28 ( fig7 ). it will be noted that base flange 24 on the underside thereof , has a recess into which is placed a sealing tape 26 . sealing tape 26 may be located merely at the nailing apertures 29 or alternatively and preferably , is provided about the circumference of base flange 24 . roof ventilator 10 also includes an inner body generally designated by reference numeral 30 . inner body 30 has a first side wall 32 and a second side wall 34 with each side wall being substantially identical and therefore only one will be described in detail herein . first side wall 32 includes a plurality of apertures 36 , each designed to receive and mate with a corresponding locking lug 22 on side wall 14 of base 12 . the engagement of locking lugs 22 with apertures 26 secures inner body 30 to the base 12 . inner body 30 also includes a relatively low front wall 38 and an arcuate back wall 40 . apertures 46 are provided to receive a pivot bar 42 which is retained in position by means of a locking cap 44 . it will be noted that there are a plurality of indicia 48 on side walls 32 , 34 for reasons which will become apparent hereinbelow . roof ventilator 10 also includes an outer body generally designated by reference numeral 50 and which outer body 50 has a first side wall 52 , a second side wall 54 , a rear wall 56 and a front wall 58 . side walls 52 , 54 are again substantially identical and thus only one will be described herein . as may be seen , side wall 52 includes a side wall front aperture 60 which is designed to align with apertures 46 to receive pivot bar 42 to thereby secure inner body 30 and outer body 50 together in a pivotable relationship . side wall 52 also has a side wall rear aperture 62 and a viewing aperture 66 for reasons which will become apparent hereinbelow . a locking pin 68 secures inner body 30 and outer body 50 in a desired position by extending through aperture 62 in side wall 52 . as may be seen in fig6 , outer body 50 is provided with rectangular cutouts 70 at the upper corners thereof . associated with cutouts 70 are diagonally extending key traps which comprise a diagonal wall 72 extending between abutting walls . a locking key 74 is provided for use at each corner . as may be seen , each locking key 74 has a lower section 76 and an upper section 80 which are offset with respect to each other . each locking key 74 has an l - shaped cross sectional configuration . on one wall of lower section 76 , there is provided a locking tongue 78 while on upper section 80 , there are provided a pair of locking tongues 82 , 83 . the roof ventilator 10 includes at least a lower section generally designated by reference numeral 84 . lower section 84 includes downwardly and outwardly sloping deflector walls 86 . extending about the inner periphery of the lower section 84 is an inner vertical wall 88 . lower section 84 further includes a diagonally extending wall 90 to define a key trap 91 in a manner similar to that described with respect to key trap 72 . situated above roof section 84 is a spacer ring generally designated by reference numeral 92 and which spacer ring 92 has a base portion 94 with spacer elements 96 extending upwardly therefrom . spacer ring 92 is sized to fit about the exterior of inner wall 88 of roof section 84 . an insect screen 98 is sized to fit interiorly of spacer elements 96 resting on the upper edge of inner wall 88 of roof section 84 . it will be noted that insect screen 98 has bevelled corners 100 to allow for placement of key locks 74 . roof ventilator 10 also includes a vent section 102 which is similar to lower section 84 in that it is provided with a sloping deflector walls 104 and an inner wall 106 . however , a roof cap 108 is mounted thereon to cover the top portion . a level indicator 110 is provided on roof cap 108 . as may be seen in fig7 , ventilation is permitted through screen 98 under deflectors 104 . also , as seen in fig7 , the unit is suitably secured to the roof by means of nails 28 or other like fastening devices which go through apertures 29 in base flange 24 . sealing is automatically provided by means of a tar seal 26 or like sealing compound . lower housing 30 is secured to base 12 through the inter - engagement of locking lugs 22 with apertures 36 . outer housing 50 is suitably secured to inner housing 30 by means of pivot bar 42 and locking cap 44 . locking pins 68 are inserted through apertures 62 in wall 52 of outer housing 50 to engage one of the apertures 49 in side wall 32 of inner housing 30 . the attachment at the correct angle may be done through the visual sighting of indicia 48 through viewing aperture 66 or alternatively , level 110 may be utilized . locking keys 74 as previously mentioned , have a single projection or locking tongue 78 which will engage with apertures 64 formed in side walls 52 , 54 . the upper portion 80 of locking keys 74 have two tongues 82 , 83 which will engage side wall 88 as may be seen in fig1 . a second set of locking keys is illustrated in fig1 and 15 and references numerals in the 200 &# 39 ; s are used for like components . thus , locking keys 274 have first and second locking tongues 282 , 283 on an upper portion thereof while there is provided a single locking tongue 278 in the lower portion . as seen in fig1 , locking tongue 278 engages rearwardly of locking tongue 83 which locking tongues 282 , 283 function to engage vertical wall 106 of vent section 102 . while there is shown only a single vent section in the above embodiment , a further vent section 202 may be added as shown in fig1 b using the same type of locking keys . in fig1 c , a ventilator having a still further vent section 302 is illustrated . it will be understood that the above described embodiment is for purposes of illustration only and that changes and modification may be made thereto without departing from the spirit and scope of the invention .