Looking for 2-hour Reminder Device

My son has trouble hearing the 2-hour BG test reminder on his pump, even 
though he has it on the loudest setting (he keeps his pump in his pocket, 
which muffles the sound). I am looking for something that he can wear on
his 
wrist or attach to his backpack that can work as a 2-hour reminder.

I considered a wrist watch; but that's a lot of work to set the alarm time

each time. I'm looking for something where he can just set a 2-hour
reminder 
from the time it's set. I was thinking that someone might have made a 
product like that for diabetics.

Has anyone ever heard of anything like that? Thanks!

Neil