This is a vintage cardboard slide rule from Jerguson Gage & Valve Co. in Burlington, Mass. This slide rule is dated 1962. Revision 2. Made by Slide-Chart. It is a Selector slide rule for Series L-10, 20 and 30 gages with valves. This slide rule measures 9 1/4" by 3 7/8". Heavy cardboard with brass rivets on the edges, securing the two outer pieces. Good condition with minor wear.