Deliberate texture marks this terminus: the Knurled End Cap (47-600PF/1H16) closes a 1.5" OD stainless railing with a cross-hatch face, press-fit inside the tube end and flush with the tube face. Pool rails, coastal deck rails, and exterior stair runs get an ending that matches their marine-grade requirements: 316 polished or satin stainless for .060" wall tubing, standing up to salt air, chlorine, and weather. Polished reads bright; satin reads softer. The cap is purely cosmetic, with no load role.