Used by the MemMaker memory-optimization program to determine the size in memory of device drivers and memory-resident programs. During optimization, MemMaker adds SIZER.EXE to the beginning of each CONFIG.SYS or AUTOEXEC.BAT command that starts a driver or program. When the optimization process is complete, MemMaker removes SIZER.EXE from each command line. This program is used exclusively by MemMaker.