Are those lifeline necklace thingies waterproof?? Like, if I got my mom one, can she wear it in the shower? (she doesnt have MS, just bad knees and bad back and not the greatest at walking anymore)

I've been thinking about talking to my dad about getting something like that for my mother, so that if I can manage to get back to school (as long as the MS trolls will let me go) I wont feel so bad about leaving her home for hours at a time alone.