The M-50 is the ESP guitar company's bottom line M-series guitar distributed by LTD (ESP's mass-produced guitar brand). The guitar is sometimes referred to as a superstrat which is a guitar shaped like the Fender Stratocaster with humbucking pickups instead of the usual single coil pickups used on the original Stratocaster.
ESP-LTD M-50
References
ESP M-50 Wikipedia(Text) CC BY-SA