Be aware that Philadelphia has some crazy laws about knives. It's mostly illegal to carry one within city limits. I spent most of my life with a Swiss Army Knife in my pocket, but that's a crime here, and I'm not relying on Krasner's discretion to avoid trouble.

From the city's Municipal Code:

§ 10-820. Cutting Weapons in Public Places. 269

   (1)   Definition.

      Cutting Weapon. Any knife or other cutting instrument which can be used as a weapon that has a cutting edge similar to that of a knife. No tool or instrument commonly or ordinarily used in a trade, profession or calling shall be considered a cutting weapon while actually being used in the active exercise of that trade, profession or calling.

   (2)   Prohibited Conduct. No person shall use or possess any cutting weapon upon the public streets or upon any public property at any time.

      (a)   Exception: This restriction shall not apply to the use and possession of cutting tools by emergency personnel of the Philadelphia Fire Department, whether on or off duty. 270

   (3)   Penalty. The penalty for violation of this Section shall be a fine of not less than three hundred dollars ($300) and imprisonment of not less than ninety days.