The interesting point here is:
It does not extend above 280 kts.
BUT ,
If you are at 37000 Ft, M 0.82 , with an indicated of , say 250 kts.....If you select it down , it comes down , because the computer only takes CAS in consideration. Not Mach.
PS :I know the max alt to extend the gear is 21000 ft, before someone comes to say it.