Kansas City Roulettes - private perforations applied to the imperforate one and two cent Washington (Franklin) stamps, Scott 408 and 409, by the postmaster of Kansas City in 1914 and 1915. According to Johl, the rouletting devices used to make the perforations were bought at a local chain store. The wheels were similar to the types seamstresses used to layout their dress patterns. These perforations are very collectible but, unfortunately, easy to manufacture. It is almost impossible to get a favorable opinion on anything less than a block of four attached to an affidavit that had been signed and notarized at the time the stamps were available.

Kansas-Nebraska Overprints - (Scott’s 658-679) 1929 Rotary Stamps, Series of 1922, overprinted Kans. or Nebr. in an effort to prevent theft of postage stamps from Post Offices. The experiment proved unsuccessful and was quickly dropped. 

Killer Cancel - a cancellation which "kills" the design of the stamp. By covering most of the design, a killer cancel insures that the stamp will not be reused .

King, Beverly - noted U.S. philatelist who, along with Johl, wrote the seminal works on early 20^th century U.S. stamps

Knife - a device that cuts stamps apart as they are fed through an affixing machine