I put this as "notification device" because I don't specifically want a smart watch or fitness band but open to recommendations.
I want to get a device for my fiancee that she can pop on her wrist and receive notifications whenever she gets a call or text. The other main aspect I'm looking for, is a solid connection to the phone. I appreciate that it's not going to be a fool-proof connection if there's enough noise in the area but hoping for something fairly robust with its connection so that she still has a chance of receiving a notification at a comic con.
Also desired is a battery life of at least a day.
She uses an Xperia Z5 Compact, which is Bluetooth 4.1. A bulky watch is not feasible as she has fairly dainty wrists - a Casio G-Shock, for comparison, wouldn't be well-suited. Changing phones isn't currently feasible.
The budget is pretty flexible - if a £20 device does the job, great. If it ends up being £300 I can work with that. £500, however, is OTT but could be doable if there's a really solid reason to go that high (though I doubt it). Best-case would be a device already available as I'm thinking of getting it at the start of next month. If there's a solid reason to hold off for two months I'll consider that too.
I'm not expecting miracles - my request includes the ability to receive notifications at a comic con, which is signal hell. I assume going too cheap would reduce the chances of a solid Bluetooth connection.
Any recommendations would be greatly appreciated.