Tubular Handrail Standard (550–550mm) – For 33.7mm, 42.4mm, or 48.3mm OD Tube The Handrail Standard is a versatile and robust component designed to support horizontal handrails using 33.7mm, 42.4mm, or 48.3mm outer diameter (OD) tubes. this standard is suitable for various applications, including industrial, commercial, and residential settings.