Section 16 Machinery and mechanical appliances; electrical equipment; parts thereof; sound recorders and reproducers, television image and sound recorders and reproducers, and parts and accessories of such articles 84 Nuclear reactors, boilers, machinery and mechanical appliances; parts thereof 84 09 Parts suitable for use solely or principally with the engines of heading 84.07 or 84.08. 84 09 91 Suitable for use solely or principally with spark-ignition internal combustion piston Commodity Code Description 84 09 91 00 Suitable for use solely or principally with spark-ignition internal combustion piston