CR-1/3N
Basically it’s like 2 of the LR44s stuck together. So gets rid of the fretting issues you get with 2 batteries rubbing against each other. Though I do still use a drop of baby oil on the contacts so that I’m covering all bases!
When everything else on my bikes is rechargeable (lights, Di2, computer) and just works it does seem very old fashioned to be having to change batteries, worrying about how low they’re getting, etc. Add in the need to order batteries (I haven’t found any local store that stocks the big ones) and then sit there with a cocktail stick and a bottle of baby oil lubing up the contact points and I have to say it’s not quite the premium product experience you expect when you pay that much money!