SOUNDTRAXX 810038 Exhaust Cam Set. The Exhaust Cam Set provides an assortment of exhaust synchronization cams that can be mounted quickly and easily to the inside face of the driver wheel, often without disassembly of the locomotive. Includes cams for 2-cylinder, shays and articulated engines. For N-Scale and larger. For use with Steam sound Decoders and the S220-IR Steam Sound System. List $10.00 For more information click on the link below. As always call to see if you qualify for any additional discounts, and to check the accuracy of your order's weight.