AFAIK you can usually make 10 contactless tap and go type payments via debit/card before being required to insert the card into the reader and enter your PIN to approve the transaction and reset the tap and go count.
Obviously you can’t insert a wrist band into a card reader so I think the reset of the count is done inside the app. I’m still waiting for my wrist band so I’ll update once I know.
From their FAQ
I’m waiting for this to come to UK which 
should be soon. Non NFC has been out for a bit.
About £30-40 quid, 12 day battery life and only 12.8 grams
Badger pay? 
iCard is a nice replacement for the bpay fob.
The only issue i have with fobs and cards on your keys is well you need to take them out your pocket like your phone which you could have tapped 
It’s rare to have keys but no phone. 
Something on your hand/wrist like a ring/band/watch is saving that fumble for your keys/phone which isn’t always ideal to be pulling out.
