The search and rescue group's chairman, Murray Johnston, said waterproof gear was vital for the volunteers.
"When you are at 1500m ... it's just one of the basic things, and it's also one of the main reasons we go to rescue people - they don't look after themselves well enough," Mr Johnston said.
Group treasurer Sam Milligan said other funding had been put towards jackets but fell short of equipping all the 20-strong team. The society was then approached and agreed to help out, with its logo to be embroidered on all the group's jackets.
"We've been involved with the bank for 30-odd years and this is the first time we've asked for sponsorship - most of the local businesses are pretty good at supporting us where they can," Mr Milligan said.
Volunteers Laura Thompson and Julie Millar said they could be sent on all sorts of missions.
"We do go out in all weather and most of the time we are deployed it's because a helicopter can't be," Mrs Millar said.
A volunteer since 2007, she said as well as the outdoors aspect, she enjoyed the chance to do something "completely different from my day job".
"Both Laura and I keep pretty fit. We run most days and we make sure we do a bit of time in the hills."
The jackets would help ensure the volunteers stayed warm and dry when they were deployed, she said.