Inside, the 990’s durable gas system and a host of corrosion-resistant internal parts/finishing (nickel boron-coated gas piston, magazine tube, hammer and sear), plus an enlarged/beveled loading port, elongated elevator, and anodized follower combine for smooth operation. Outside, there’s the ergonomically-designed AfterShock grip with rubberized palm pad, a streamlined forend with Mossberg signature texturing, and an embossed strap for a solid hold; plus a magazine tube extension with M-LOK® mounting slots on the sides and bottom for easy accessory flexibility. Mossberg 990 Aftershock 12ga 18.5" Bbl Black 5+1 Shotgun w/ Aftershock Grip/Strapped Forend/M-Lok 83002