Shotgun: Mossberg - Optic: TG / VOR / DOC - Fits TRU TEC Micro (TG8100B TG8100G) EOTECH DOCTER INSIGHT MEOPTA & VORTEX VIPER and other optics with a similar 4-post mount. - Fits Mossberg 500 590 590A1 930 - Mount a dot-optic on drilled and tapped Mossberg receivers - Does not require a Picatinny rail - Mounting hardware and tools included - Allows optic to sit low on the receiver - Lightweight / compact design