- 4-Post Adjustable Rack Shelf. 2 RMS - Durable steel construction - Black textured powder coated - Supports up to 125 pounds (lbs.) load - Designed to fit standard 4-post 19" distribution racks - Rack shelf length adjustable from 27" to 32" - Two (2) Rack Mount Spaces (RMS) - Compatible with ICC 4-post distribution rack ICCMSR4P84