Setup Auto-Reorder & Always Have the Safety Supplies You Need On-Hand. S251 5X Class 2 Poly Mesh/Lower Solid Front Surveyor Hi Viz Lime Vest ERB Safety's S251 Class 2 vest is made of ERB Safety's S251 Class 2 vest is made of 100% polyester mesh with solid fabric panels on lower front. A zippered pocket on back is large enough to accommodate a clipboard..