Aluminum RW90 is a cross linked polyethylene insulated single conductor. The available size range is from #8 AWG to 750 kcmil. Aluminum RWU90 is a cross linked polyethylene insulated single conductor also. The insulation is thicker than that of the RW90 making it suitable for direct earth burial. Aluminum feeder cable is a twisted assembly containing RW90 singles. in 3 or 4 conductor configurations, with or without an isulated ground.