The Encyclopedic Gear Set is 7 x 7 inches (15 x 15 cm) and contains 41 gears. The gears include 2 of every gear size from 12-30 teeth. Each size of gear has an 'A' design and a 'B' design.
The difference between the A gears and the B gears is that the placement of the holes relative to the gear teeth is shifted. If the A design holes line up with a tooth the B design holes will line up with a gap between teeth. This feature is necessary for making designs involving epitrochoids and hypotorchoids that lineup. Without the A and B gears any complex designs that use both epitrochoids and hypotrochoids (40-12 ring-gear and 40-12 gear-gear for example) will have the two components misaligned by a small amount.
This gear set also includes, for the first time, 1.5 mm pen holes, in addition to other sizes. Other gear sets include 3, 6, and 10 mm pen holes. These smaller pen holes allow for a wider range of design options and closer hole spacing.
Not all pens fit into 1.5 mm pen holes although there are many readily available pens that do. Pens with a metal barrel tip will usually work.