The "C" indicates small format IC core, which is the only core style Falcon products. The C987 will be provided less core unless -6, or -7 suffix is specified (6 or 7 pin core)
Example:...
This only applies to the full size interchangeable cores. The SFIC mortise cylinders have part numbers for housings with construction cores (Disposable and Keyed).
Simply add (-ICX) to the end o...