The protobactin cyclinder was a piece of equipment that was issued to members of Division Cloud Force, a Cularin Militia unit that was established during the time of the Clone Wars.
Sources
Cloud Force on Wizards.com (original site is defunct)
The protobactin cyclinder was a piece of equipment that was issued to members of Division Cloud Force, a Cularin Militia unit that was established during the time of the Clone Wars.
Cloud Force on Wizards.com (original site is defunct)