TRIPP LITE's SR4POST the 45U 4-Post SmartRack open frame rack organize and secure network rack equipment is made of black steel with square, numbered mounting holes. The unit consists of toolles button holes to accept PDU's or cable maangers. The SmartRack 4-post is ideal for those looking for a cost conscious 19 in rack mount solution. Multiple units can be bolted together side by side. The unit is RoHS compliant.