Recommended for indoor or outdoor bulk cylinder storage, barricade racks surround cylinders with 2-in (51-mm) square steel structural tubing, continuously seam welded at all junction points and sealed with exterior grade powder-coat paint for long lasting strength, durability and dependability. Tops ground smooth and capped with high-density polyethylene (HDPE) caps to prevent corrosion and injuries. Features two levels of welded steel chains for each cylinder and clasps to connect the chains to the rack, ensuring a snug fit. Pre-drilled 0.531-in (14-mm) diameter floor mounting holes included on lower tube structure. For seismic installations, add Model 35350 S4-rated anchor bolts (not included).