I’ve used something like this for my battery for the Garmin.
https://www.wiggle.co.uk/topeak-drybag-for-iphone-6/?lang=en&curr=GBP&dest=1&sku=487281&kpid=487281&utm_source=google&utm_term=&utm_campaign=Shopping+-+All+Products&utm_medium=base&utm_content=mckv|sMz3ETodu_dm|mcrid|295268872713|mkw||mmt||mrd|487281uk|mslid||&mkwid=sMz3ETodu_dm&pcrid=295268872713&prd=487281uk&pgrid=60973103002&ptaid=pla-520815088926&gclid=EAIaIQobChMIiPfT0LGj5QIVybTtCh2uqg2mEAQYASABEgLkdfD_BwE
@fussballclub started
London Fixed Gear and Single-Speed is a community of predominantly fixed gear and single-speed cyclists in and around London, UK.
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I’ve used something like this for my battery for the Garmin.
https://www.wiggle.co.uk/topeak-drybag-for-iphone-6/?lang=en&curr=GBP&dest=1&sku=487281&kpid=487281&utm_source=google&utm_term=&utm_campaign=Shopping+-+All+Products&utm_medium=base&utm_content=mckv|sMz3ETodu_dm|mcrid|295268872713|mkw||mmt||mrd|487281uk|mslid||&mkwid=sMz3ETodu_dm&pcrid=295268872713&prd=487281uk&pgrid=60973103002&ptaid=pla-520815088926&gclid=EAIaIQobChMIiPfT0LGj5QIVybTtCh2uqg2mEAQYASABEgLkdfD_BwE