This paper discusses the case which involved the battle between Gillette's MACH3 three-blade razor and Schick's QUATTRO four-blade razor. Gilette had sued Schick for patent infringement in its hometown of Boston. Gillette's patent had only one independent claim, and it called for a safety razor comprising a group of first, second, and third blades. Schick's position was simple its razor had four blades, not a group of three blades, Gillette's position was also simple - it said that its claim required at least three blades but was not limited to just three blades. The Boston court sided with Schick which concluded that Gillette's invention was limited to just three blades. Gillette appealed to the CAFC. There, it argued that its claim language should be read as open language permitting the incorporation of additional elements, including additional blades in the claimed razor. It relied on two words in its independent claim, which Gillette said signaled the claim's openness, namely, the word comprising and the word group. Schick, on the other hand, argued to the CAFC that the Boston court had been right and Gillette was elevating form over substance, since Gillette's patent was filled with references to three-blade razors but did not have a single specific mention of a four-, or more, blade razor. The CAFC struggled with the closeness of these competing arguments. In the end, the two-member majority agreed with Gillette's arguments regarding the use of the words comprising and group. This case serves as a lesson that one must be very careful about what one says about an adverse patent in a public forum.