The Mossberg 500 Mariner is the corrosion-resistant variant with Marinecote nickel finish on all metal surfaces. 18.5-inch cylinder-bore barrel. Designed for boat and marine environments. Synthetic stock. Popular with offshore fishermen and coastal homeowners. Type: Pump Shotgun Action: Pump-Action Caliber: 12 Gauge Capacity: 5 Year introduced: 1987, USA Weight: 6.5 oz Overall length: 28" Status: Active Intended use: Home Defense, Marine, Tactical