What is a recommended USB memory device for the E4980A and the E4981A?

4 GB USB Memory (Keysight PN 1819-0637) is recommended in place of the discontinued 64 MB (Keysight PN 1818-8989), 512 MB USB Memory (Keysight PN 1819-0195), 1 GB USB Memory (Keysight PN 1819-0375), 4 GB USB Memory (Keysight PN 1819-0514) and 16 GB USB Memory (Keysight PN 1819-1235) devices. The PN 1819-0240 256 MB USB Memory cannot be used with the E4980A and the E4981A because it does not function with the save/recall operation on the E4980A and the E4981A.