screen 16 does not require the addition of an electrical insulator because the at least one locking tabs 22 are themselves made in the exemplary embodiment from an insulating material but more importantly the free edge 34 of the screen 16 does not face toward the dissimilar metal in the exemplary embodiment aluminum of the upper and lower interior walls 36 and 38 of the channel 18 of the frame members 14 but instead faces toward one of the planer edge faces 64 of the at least one locking tabs 22 thereby preventing dielectric corrosion in addition more force can be applied to edge hem 30 of the screen 16 of the present invention without distortion of free edge 34 during tensioning of the screen 16 as compared to for example a perpendicular lip as may be found in some prior art designs this is important because a more highly tensioned screen 16 improves the aesthetics of the finished product and for security screen applications can withstand greater impact due m it 39 s improved pullout strength the screen 16 of the present invention 10 may also be more centrally located within the frame 12 preventing an imbalance of the sealing gasket 24 and retention 20 gasket thicknesses which.