A content addressable memory device. The meat classification system comprises a split dual-belt conveyor system and a probetrolley mechanism assembly where the probe is operable to penetrate the meat cut for measuring fat thickness as the meat cut is being conveyed along the dual belts. 016 \u03a9 or below formed by stranding several tens of wires which are conductive wires coated with an insulator into a predetermined thickness. Switched to a second status, a shutdown signal is output to the MCU to shutdown the electronic device; and the second switch module further outputs a second control signal to switch off the first switch after a determined time period, to cut power consumption to nil at the end of that period. The projection and light exposure apparatus automatically detects the image magnification and, based on the detection result, adjusts the positions of the second and fifth lens groups G2 and G5 as a unit so as to maintain a specified magnification.