Selective Pallet Racking uses the FIFO (First in First out) principle and is the simplest form of Pallet Racking. Its the only type of racking that can offer 100% access to any pallet in your system at any point in time. SR racking is generally designed as Single or back-to-back rows of racks with an aisle wide enough for a fork lift truck. Since SR takes up the maximum amount of space in a warehouse when installed it is used to benchmark the capacity of the warehouse before comparing it with any other system to understand increase in capacities.