The Delta Prevention SGTR4201 aluminum guardrail kit for roof skylights can be installed on skylights with curb dimensions up to 42" x 42". A minimum vertical profile of 3" is required for the installation. This modular kit is engineered with heavy-duty 1.9" OD anodized aluminum tubes for corrosion resistance and a durable architectural appearance. It features our unique clamp-on system providing a 100% perforation free installation. Complies with OSHA 1910 General Industry Standards and 1926 Subpart M Construction Standards.