Spiroll Parallel Straightedges, Drawing Protectors, and Blueprint Protectors
As of 2011, Spiroll International is no longer in business and produces no products at this time.
In case you're wondering, Spiroll used to manufacuture very nice high-quality portable drawing boards. They also made the Spiroliner Parallel Straightedges for their portable drawing boards, which also fit traditional full-size drafting tables. Spiroll also manufactured Drawing Protectors that mounted to the front edge of a drafting table.