The Karbonn K140 is a low‑cost Android smartphone that originally shipped with the POP (Proprietary Operating Platform) firmware . Enthusiasts often replace the POP ROM with a stock Android build or a custom ROM to gain better performance, newer Android versions, and access to Google Play services. The “flash file” refers to the packaged firmware image (usually a .zip or .tar archive) that can be installed via a flashing tool. Common Flash File Types | File Extension | Typical Use | How It’s Applied | |----------------|-------------|------------------| | .zip (fastboot) | Stock or custom Android ROMs | Flashed with fastboot flash commands or via recovery (e.g., TWRP) | | .tar (SP Flash Tool) | MediaTek (MTK) firmware for POP devices | Flashed with SP Flash Tool on a Windows PC | | .img (raw image) | Individual partitions (boot, system, recovery) | Flashed with fastboot flash <partition> <file>.img |