Alvin - Universal Bow Compass with Adapter - The Alvin Universal Bow Compass with Adapter has a fiberglass ringhead and pivot gear design for smooth adjustment. The Universal Bow Compass wedge clamp holds technical pens, lead holders, pencils, ballpoints, cutting knives, and fineline markers. Center wheel adjustment is fast and precise. This Universal Bow Compass has a black enamel finish. Alvin is one of the primary sources for drafting supplies and drawing equipment in the country. Creative Coldsnow is a pround retailer of Alvin graphic arts, drafting and fine arts products.