I'm pretty sure you use the same on off switch. OPnce for normal lite then the next time you swith it up it goes into strobe mode.
Guys be aware the battery compartment has a nasty habit of falling too bits. The little bits of wire break inside it. Also the blue flimsy plastic infa red? screen often breaks as well.
The old 4FR is a tried and true piece of kit. The MS2000 is a flimsy piece of crap. My opinion.