Some DVRs are now small enough to hide them behind the rear view camera. THis older Costar DVR is 4 times larger than the new SD4m Mini series which is so much easier to hide in any vehicle. For most applications of school bus cameras, digital bus video cameras, vehicle camera, mobile video surveillance systems, digital in-car video camera, in-car camera, bus camera surveillance the best value is 100% Solid State digital like the SD4m series due to their tiny size and footprint.