RAM® 方形柱夾具底座，適用於寬達5吋的柱子，不含五金

This thing clamps tight onto the 3-inch rail on my boat without any slipping. The rubber ball holds my device steady even when I hit some chop.

The 1.5" rubber ball locks into my existing mounts perfectly, and the clamp handles my 4" square rail without any wobble. Solid build, exactly what I needed for a permanent install.

The rubber ball snapped right into my existing mount arm without any fuss, and the clamp grips my square tubing perfectly. I was worried about the width, but it handles my 4-inch post with room to spare.