mounting holes 62 in wall 43 of outturned flange 49 and anchored in wall 80 wall 43 terminates in a longitudinal lip 60 which preferably extends perpendicularly outward from the margin thereof a flange 47 projects perpendicularly from wall 45 and terminates in a groove part 58 walls 43 and 45 are enclosed by a cover member 46 which is generally l shaped cover member 46 includes a longitudinal marginal u shaped part 54 which fits around lip 60 and an opposite marginal hook part 56 which attaches to groove part 58 cover member 46 is retained in place by u shaped part 54 straddling lip 60 and the interlock of hook part 56 with groove part 58 with screws 63 being hidden from view frame assembly 40 is easily adjusted within the opening by simple removal and replacement of screws 63 outer frame 42 provides for a longitudinal u shaped channel part 57 which secures window glazing panel 64 in place by use of a gasket 59 a second window glazing panel 66 is configured to be set in preformed grooves which run horizontally along the top and bottom of frame assembly 40 panel 66 is secured in channel part 53 within a gasket 59 39 and may be slid horizontally relative to panel 64 channel part 53.