RAM MOUNTS RAM-D-313-DU D-Size 2.25 inch Ball Base with 1 inch Rail Mount for 1 inch to 1.25 inch Rails

Built around a 2.25-inch D-size ball, this RAM-D-313-DU base delivers rock-solid mounting for heavy electronics on rails from 1 to 1.25 inches in diameter. The marine-grade powder-coated aluminum construction shrugs off corrosion, vibration, and the harshest environments, making it a go-to for boats, trucks, and industrial rigs.

Overview

The RAM-D-313-DU is a rail mount base engineered for RAM D-size components. It clamps onto round or square rails and bars with an included U-bolt, two nuts, and two rubber caps. The 2.25-inch ball provides a secure pivot point for arms and device holders, supporting heavy-duty loads without slipping. Its black powder-coated finish resists scratches and corrosion, while the aluminum body keeps weight manageable without sacrificing strength.

What stands out

• D-size 2.25" ball for maximum stability with heavy devices
• Fits rails from 1" to 1.25" diameter — round or square
• Marine-grade aluminum with corrosion-resistant powder coating
• Includes U-bolt, nuts, and rubber caps for secure, non-marring installation
• High vibration resistance for off-road, marine, and industrial use

Technical details

• Ball Size: D (2.25 inch / 57.15 mm)
• Material: Marine-grade powder-coated aluminum
• Color: Black
• Compatible Rail Diameter: 1" – 1.25" (25.4 mm – 31.75 mm)
• Mounting Hardware: U-bolt, 2 nuts, 2 rubber caps
• System Compatibility: RAM D Size components
• Load Rating: Heavy Duty
• Corrosion Resistance: Yes
• Vibration Resistance: High
• Application Environment: Marine, Automotive, Industrial

Our verdict

The RAM-D-313-DU is a rugged, reliable rail mount base that excels in demanding environments. Its D-size ball and corrosion-resistant build make it a top choice for heavy-duty mounting on rails.