Mark XV explained

Mark XV or Mark 15 often refers to the 15th version of a product, frequently military hardware. "Mark", meaning "model" or "variant", can be abbreviated "Mk."

Mark XV or Mark 15 may refer to:

Technology

a designation reserved for use with the Supermarine Seafire
1950s American thermonuclear bomb
automated anti-missile gatling gun, entered US Navy service in 1980

Other uses