a Portage pack is a dry bag with shoulder straps.. they tend to be big ..

But here is one made for 'commuting'

30 years ago I got a simpler one , I use it for carrying my mandolin in its wooden case, in PNW rain.

brands : Sealine, Seattle sports 'Bolt' shows MSRP @ $85..

REI sells them ..




[NB: Summer, your back will get very sweaty..]



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