flange 26 and has a lower open area 77 below flange 26 as seen in fig3 flange 26 is generally aligned with lower flange 15 a lock 78 may be provided at the top of door 73 removably locking door 73 to top wall 44 the configuration of base 43 of box 12 is such that it can fit within framework 13 as shown in fig1 side walls 15 to 17 may extend upwardly a sufficient distance to accommodate box 12 and hold it in place as seen in fig3 as seen in fig1 an elongated panel 79 which may also be perforated is slid between flange 60 61 until it abuts against screw 64 panel 79 may have a cut out section 79 39 where it abuts against screw 64 for receiving screw 64 therein tightening of wing nut 69 thus tightens plates 62 63 in any desired location along tracks 58 59 panel 79 has a flange plate 84 fig3 secured to the end opposite section 79 39 with an inwardly extending lip 82 at its lower end panel 35 is mounted to brackets 31 33 by spaced side flanges 82 83 see also fig1 top flange 32 and bottom flange 85 lip 82 thus extends under top flange 32 fig3 and abuts against panel 35 to firmly hold panel 79 to mounting structure 11 if it is desired to close off the opening 72 fig1 leading into box 12 a removable.